Automotive Air Conditioning Information Forum (Archives)

Provided by www.ACkits.com

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Electric fan and A/C not cooling well Pages: 12

ariff on Wed June 09, 2010 11:44 AM User is offline

Year: 2001
Make: Jeep
Model: Cherokee
Engine Size: 4.0
Refrigerant Type: r134a
Country of Origin: United States

Hey guys,
With the help of my mechanic I have been trying to get my A/C working properly. It is going on a month now of trying to get it fixed. I have done all the labor, replaced the compressor, accumulator, and orifice tube. My mechanic has done the evacuating and charging. Last week I had him charge it and it was cool, about 62 degrees, but not cold like it should be. I took it back to him today and he said it was a bit low. So he charged it and checked for leaks. He found a very small one around the fill plug on the compressor. He did not seemed very worried about it. His concern was that the aux cooling fan was not coming on when the compressor was turned on. Is this the way it should work? Should the aux fan come on with the compressor? Remain on as the compressor is on, and turn off once the compressor shuts off? Or should it come on at desired temps as the PCM sees fit? This is on a 2001 Cherokee, from my research I found this from the FSM for the 2001 cherokee:

The electric cooling fan comes on when coolant temp is at least 223* and remains on until the temp drops to 217* or below. The electric cooling fan comes on when the A/C pressure reaches 300 +/- 20 PSI and will continue to run until pressure drops to 235PSI.

I believe the Aux fan use to come on all the time when the A/C was turned on in older Cherokees up to 1999. In 2000 they cahanged this to the description I listed above.
My mechanic suggested I replace the high and low pressure switches. He thinks that these switches are causing the fan not to properly run and cool the condenser. He did test the electric aux fan and says it works. Is there a way to test these switches? I hate replacing parts that don't need replaced. Thanks for any help.

bohica2xo on Wed June 09, 2010 2:44 PM User is offline

Pressures & temperatures will tell you what the switches are doing.

Those fan parameters are awful. No fan until the engine is so hot it is killing every piece of plastic in the engine bay. No fan until the refrigerant is over 300 psi? That means you depend on the mechanical fan to do most of the work. Your fan clutch is probably shot, unless you have replaced it within the last 10k miles.

Check the fan clutch, or replace it if it is original.

Post the pressures if you can, but at least give us a clue about the ambient temps when you were seeing 62f vents.

B.



-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Wed June 09, 2010 3:16 PM User is offline

Thanks for the reply.. I am not sure what my high side and low side press. are since I did not see them. I had my mechanic do this for me. I can ask him though. The temp outside when I got the 62* from the A/C was about 85*
I have checked the fan clutch and had my mechanic check it. It appears to be good. He also mentioned that the mechanical fan is used mainly for cooling the radiator and the electric fan is used for the condenser. I have been looking into a way to wire in a manual switch to turn on the electric fan when I want. I have had a hard time finding a good solution for this without setting of a CEL on my 2001. Earlier models it is preatty easy to do.

bohica2xo on Thu June 10, 2010 1:21 PM User is offline

The mechanical fan represents 50% or more of the airflow across the evaporator / radiator package in that vehicle.

If you do not know the history of the clutch, I would recommend a quality replacement. It can extend the life of underhood components.

The electric fan can be controlled by adding a pair of relays to the circuit. The PCM then controls a relay coil, and can switch the fan normally. The second relay can be controlled by the compressor clutch circuit, to turn it on anytime the compressor is running.

Make sure the air path through the heat exchanger stack is clean. Accumulated road dirt, bugs, etc. can reduce airflow & heat transfer. Be careful not to bend the fins when cleaning. I recommend soaking a clod heat exchanger with a cleaner like Simple Green or Zep Citrus at full strength. Spray it deep into the fins, and let it soak for a few minutes before rinsing with a garden hose.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Sat June 12, 2010 1:24 AM User is offline

I thought I'd post back some more results.. Since I finally picked up a set of gauges. Doing so has been very helpful for me to see with my own eyes what is going on. I came to the conclusion my mechanic may not know what is going on. I also picked up a new high pressure switch from our CARQUEST. Total price was 50 bucks. I was still not 100% convinced this was causing my problem. So I left it in the package and went to Harbor Freight and picked up a set of gauges on sale for 20 bucks.. Not the best gauges in the world, but they'll work for me. So here are my results.

Static pressure: 96 PSI on the low side and 100 on the high side.
High side: 250-300 PSI fluctuates at idle, when rev'd to 1500-2000 RPM it will get as high as 340-375 PSI and the AUX fan kicks in and it drops back down to around 275 PSI and the fan stops.
Low Side: 40-42 PSI

These tests were done when it was 86* outside with about 60% humidity. Temps at the front of the condenser were around 100-120* and inside cabin temps were around 63* max recirculated air.

I also took the liberty to snap a few pics and some video so you can see what I am seeing. I really hope you can help me or have some more suggestions on what to do next. It appears the High pressure switch is working correctly, so I'll be returning the one I got from the parts store and get my 50 bucks back. If I have to take it in again to a mechanic I think I'll go elsewhere. Here is a link to the pics and video.
http://www.amrcreative.com/ariff/cars/jeep/AC/

Thanks!
I am pretty darn certin that the fan clutch is working properly after testing it several different ways. I might also add that I let the Jeep get up to operating temp with Max AC on. I then took a garden hose set it on mist and sprayed it on the condenser. There was no real change in cabin temps.

Edited: Sat June 12, 2010 at 1:30 AM by ariff

bohica2xo on Sat June 12, 2010 2:29 AM User is offline

The mist test is best done with the gauges connected, the pressure drop should be immediate.

You can also put the gauges on & go for a drive - with the gauges visible through the windshield.

The fact that the electric fan drops 100 psi of head pressure says you have an airflow problem.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Sat June 12, 2010 2:37 AM User is offline

How much should the aux fan drop the high side pressure? I will try the mist test with the gauges connected tomorrow as well as clean the condenser as you suggested. I am not sure how i can safely drive with the gauges hanging out side the car? Does the temp of 100-115* at the condenser seem high or about right?

bohica2xo on Sat June 12, 2010 3:28 AM User is offline

I usually duct tape the gauge set to the windshield so I can read them, but you could hold them on the passenger side & let someone else drive.

At 86f ambient, the high side should not be hitting 375 psi. As a general "rule of thumb" an MVAC system should have high side pressures 2.2 to 2.7 times ambient air temperature.

Your system is about twice that range. If you were to encounter 115f ambients it would be cycling on the HPCO at best. It was designed to deal with ambients like that when new.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Sat June 12, 2010 1:32 PM User is offline

Humm.. I think I understand what you are saying. But I am not real sure what could be causing the problem? Could it be the HPCO switch is really bad? Or the condenser is bad? I had my mechanic flust the condenser when I replaced the parts. He said it looked good? I am going to clean it today and try the mist test and I'll report back my findings. This AC stuff is confusing ;>) But I am learning a lot. Thanks for your help!

ariff on Sat June 12, 2010 6:06 PM User is offline

OK a little more troubleshooting this afternoon to report back on. I cleaned out the condenser with simple green and a toothbrush. Got rid of any bugs (there were not many) and cleaned all the dirt out of there. The water was pretty dirty. I also wanted to be sure the fan was pulling air through the condenser. I was able to place a magizine on the condenser and the fan was pulling enough air to suck it to the condenser. I hooked up my gauges and the low side always stayed around 30-40 PSI. High sid was still around 200-250. It was pretty cool here today 80* it rained all morning. Once I applied a mist of water to the condenser I could get it to drop to 150 PSI. However the cabin temps never got below 58*. That was the coldest I could get it. High pressure switch still comes on right at around 325 PSI and the Aux fan kicks in. I am really at a loss on what to do? Anymore suggestions?
Thanks..

bohica2xo on Sun June 13, 2010 7:51 PM User is offline

First, forget about the vent temps for now. The system pressures are your first concern, and indicate the cooling available at the evaporator. High vent temps can be caused by things outside of the refrigerant loop.

You never stated why the parts were replaced. Was this a catastrophic failure of a compressor? The serpentine & parallel flow condensors can have blocked passes from a failed compressor's debris field. Such blockage is virtually impossible to flush without specialized equipment.

You stated that the mechanic "flushed" the condensor. With what solvent & equipment?

I would road test the vehicle. 40 to 50 mph, select a gear that gives 1500 to 2500 engine rpm. Check the pressures, and post the results.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Sun June 13, 2010 10:17 PM User is offline

It was determined that my compressor was faulty by my mechanic. It had leaking seals on the front shaft and PRV. I was having problems with the pressure relief valve venting and spraying refrig. oil all over the place. I replaced the Accumulator, Liquid line\orifice tube and compressor. I am not sure what my mechanic used to flush the components with. He did say they use a special solvent and balst it through the evap, lines, and condenser with filtered compressed air. I had asked if he saw anything that looked suspect when flushing and he said everything looked clean and good. I also cut open my old liquid line and inspected the filter. It looked clean with no deposits. I'll see if I can rig the gauges up so I can road test the truck and post back my results. Thanks again for your help..

ariff on Tue June 15, 2010 11:25 AM User is offline

So I hooked up the gauges and took the Jeep for a drive as suggested. The high side moved from about 200-300 PSI and the low side stayed right around 30-40 PSI. Does this sound out of wack? Outside temps were around 80-85* The high seems a bight high to me it should be around 160-200 right?

bohica2xo on Tue June 15, 2010 12:45 PM User is offline

So you are saying that the high side dropped from 300 to 200 when you went from stopped to moving 45 mph?

A high side of 200 to 220 on that vehicle while moving (with the cabin fan on high) would be expected if the ambient was 85f with some humidity.

If you meant something else, let me know.

B

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Tue June 15, 2010 3:09 PM User is offline

OK so when I backed out of the driveway and idled out the High side went up to around 350 PSI. Once I got moving about 10MPH it returned to around 250PSI. Once on the road around 40 MPH 1800-2000 RPM the high side would move from 200PSI to 300PSI every few seconds Like clockwork. The high side was never steady at a specific pressure. But I don't think it is supposed to be right? I also checked my blend door to be sure it was working it appears to be moving when the temp is adjusted. AC was on high recirc. this entire time.

bohica2xo on Tue June 15, 2010 10:40 PM User is offline

Actually, the high side should have been stable around 200 psi.

You were watching the aux fan cycle on pressure 200 off, 300 on...

Generally at 40+ mph there is enough ram air to get the job done even if the fan clutch is shot. Your evaporator seems to need all the air it can get just to hold 200 psi.

There are a few choices for the cause of this:

1) Too much oil in the system. A replacement compressor with a full charge of oil installed along with a proper oil charge added to the system.

2) A substantial amount of liquid flush remaining in the system after flushing.

3) Overcharge of refrigerant, robbing you of condensor capacity.

4) A few blocked passages in the condensor.


Since you have cleaned the condensor, I can rule out the condensor so plugged with dust/oil/bugs/mud that no air gets through it.


You misted water on the condensor, and saw pressures in the 150 psi range. You replaced a working compressor, which reduces the odds of a blocked condensor.

The two most likely issues are too much oil, or refrigerant. Or perhaps flush. Do you happen to recall the low side pressures when you misted the condensor?

Did your mechanic charge the system by weight? If it has too much oil, a proper charge weight will not cool well. Get him to recover it, and charge the proper weight before you decide that it has any other problems. Refrigerant can be charged & recovered without changing anything else, and is the lowest cost diagnostic at this point in the tree.

If with the proper weight of charge it is the same (or worse), then there is either too much of something else in the system - or the condensor is bad.

A new Condensor for that Cherokee is 130 bucks.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Tue June 15, 2010 11:35 PM User is offline

OK this has really been a learning experience for me. And I enjoy working on cars and learning new things about them. So thanks for teaching me! When the compressor was replaced it came charged from the vendor I purchased it from. I asked my mechanic how they would add the proper amount of oil to the system since I replaced the accumulator and had the system flushed. He said that their machine did that and assured me the correct amount of oil would get put back in. The copmressor had PAG 100 oil in it. I informed him of that as well. I hope there is not left over solvent in the system. I also expressed my concern about this and he assured me they would purge all solvent from the system with filtered shop air. My mechanic did charge the system by weight, he said it was a little under 2LBS I think. As for the low side pressure when misting the condenser if I recall correctly it was around 30PSI. I like this mechanic I have been taking it to, but I am wondering if I should take it elsewhere for a second opinion? It is supposed to get up in the mid 90's by the end of the week. I'll check my pressures at that time as well.

bohica2xo on Tue June 15, 2010 11:52 PM User is offline

Well, if it was machine charged by weight it probably has the correct charge.

With a pre-charged compressor, and "the machine does that"... a very good chance it has a double oil charge. Which will make cool poorly.

If you trust your mechanic, you should discuss this with him.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Wed June 16, 2010 12:00 AM User is offline

When the system is evacuated is the oil removed? So can most of the oil be removed and re-filled with the proper amount? It is possible he did not know the compressor was already charged. Even though I did tell them this. But the word may not have gotten passed down from the counter guy to him. I trust him, but last time I talked to him he told me to replace both the high and low pressure switches. From what I can tell these switches are working correctly. So I don't want to step on his toes and tell him he was wrong and how to do his job.

bohica2xo on Wed June 16, 2010 10:54 PM User is offline

Unfortunately, recovery will not remove the oil.

Once the refrigerant has been recovered, your next move would be to remove the dryer. Turn it upside down in a container, and see how much oil drains out - let it drain for 15 to 20 minutes. Measure the oil. If it is an ounce or two, the oil charge may be ok. If you get 3 to 5 ounces (or more) of oil back from the dryer - that is your problem.

The only real way to know how much oil is in the system is a flush to bare metal & charging the proper oil charge. Do NOT flush the compressor, Just spin it by hand for 6 to 10 revolutions with the lines disconnected.

Be honest with your mechanic. The switches seem to work properly. You have a bunch of system data that would take him time to collect. Share that info with him. Explain why you believe it is simply too much oil. With jobs like this, sometimes things get dropped. Just be reasonable with the guy, and he will probably work with you on it. At this point you know more about the system than he does...

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ariff on Thu June 17, 2010 12:10 AM User is offline

OK sounds good.. I tried today to talk with him, but he was out of town. I'll stop by the shop tomorrow and hopefully will catch while he is there him. Thanks again for all your help. I can now go talk to my mechanic and not feel totally in the dark about what is going on. I'll be sure to post back what I find out.

ariff on Tue June 29, 2010 4:12 PM User is offline

I just wanted to report back on my progress. Sorry it has been awhile, family vacation. My old mechaninc now refused to work on it anymore. So I took it elsewherer and I had the system evacuated. I then removed the accumulator and poured out about 2.5oz of oil from from it. However there was probably a good 1.5 oz in there I could hear sloshing around, but could not get it to drain out. So I suspect there was 3.5 to 4 oz in the accumulator. I left the sloshing around oil in there and installed everything and gave the A\C a charge. So far everything seems to be working well. I had it down to around 45* on my way to work this afternoon. Hopefully it will continue to cool well. Thanks for your help!

bohica2xo on Wed June 30, 2010 1:45 AM User is offline

Too much oil will hurt cooling, and of course too little will kill the compressor.

Chances are you had a double charge of oil on board, given the history of this system. Removing a couple of ounces should not hurt things if that was the case.

Glad you finally got an answer to what was causing the poor cooling. A flat refusal to rectify an issue is also an answer... hope you find a better mechanic.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.