Automotive Air Conditioning Information Forum (Archives)

diyman on Tue July 26, 2011 1:32 PM

Year: 1990
Make: Honda
Model: Accord LX
Engine Size: 2.2l
Refrigerant Type: R134a
Ambient Temp: 85F
Pressure Low: 15 psi
Pressure High: Low
Country of Origin: United States

Had vacuum pulled for one hour and sit for overnight with no sign of leaking. Charged R134a refrigerant to 80% of system's required regrigerant, clutch runs about 30-60 seconds then stop. No cold air comes out from vent. Charged to 85%, no differences. Charged to 100%, no differences. Clutch sometimes run and sometimes doesn't. Low side reading is about 15 psi and high side reading is low. How can I bypass dual presure cut off switch to engage clutch?

mk378 on Tue July 26, 2011 2:23 PM

What makes you conclude the switch is why it cuts off? Sometimes runs and sometimes doesn't is often the clutch gap.

GM Tech on Tue July 26, 2011 3:42 PM

You are most likely plugged up.....

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

diyman on Tue July 26, 2011 6:00 PM

mk378, before R134a conversion this past weekend, I used retrofit kit to convert from R12 to R134a by reclaimed all R12 in the system, then filled R134a refrigerant with ester oil. It works for a couple years. Due to system has a slow low side valve leak, it only works for about 20 minutes for cool air (not cold) then hot air every time I turn it on. Once it gets hot air, it stays hot air for the rest of day until long period time of park most likely next day. I had it checked and mechanic says expansive valve has partial plugged and compressor has some leaks. Therefore, I did retrofit on this past weekend by replacing all O-rings in the system, air blow evaporator & condensor, changed new expansive valve and new reciver drier (added 1.5 oz ester oil), and changed compressor seal & added about 2.5 oz ester oil (since it is still working before retrofit). Then, after procedures described in the earlier posting. I saw some posting say the operating pressure are different between R12 and R134a. Could it be the pressure cut off switch problem or compressor has too much oil? I would like to try bypass cut off switch to engage clutch to see whether it will blow out cold air or not. Or, does anyone has any suggestions?

JJM on Tue July 26, 2011 10:35 PM

Even with a proper retrofit, these vehicles don't retrofit well and should stay R-12. With a retrofit kit, you can't expect very much, other than a total system replacement down the road.

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com

diyman on Thu July 28, 2011 2:49 PM

I am still waiting for someone who can tell me how to manually engage compressor clutch. Thanks in advance!

fisyyma on Thu July 28, 2011 5:31 PM

I would bridge out the clutch relay to manually engage the clutch. keep an eye on the pressures though because there is no safety cut out if you do that. You could use a small length of wire to do this or alternatively use a longer length with a momentary switch so you can sit in the cab to bring the clutch in and out while monitoring the pressures on the high side and low side guages while keeping an eye on the vent outlet temperature.

More often than not relay terminals are numbered:

30 = 12v from battery
87 = 12v out to clutch

These are the terminals that you will need to bridge on the relay socket.

diyman on Thu July 28, 2011 5:57 PM

Thanks fisyyma! What do you mean by "30 = 12v from battery" and "87 = 12v out to clutch"? What will happen if I let clutch keeps running without cut it off?

fisyyma on Thu July 28, 2011 9:20 PM

If you locate the clutch relay which is usually fitted within the fuse box under the hood, unplug it and you will usually find that the terminals are numbered as follows

-30 = constant [positive (+)] power (usually wired directly to car battery)
-85 = coil ground (wired to the negative (-) battery terminal or any grounded metal panel in the car)
-86 = coil power (wired to the control source. could be a switch, or it could be the car's IGN or ACC circuit.)
-87 = switched [positive (+)] power output. (when the relay coil is powered, lead/pin 87 is connected to lead/pin 30)
-87a = [on 5 lead/pin relays only] this lead/pin is connected to lead/pin 30 when the coil is NOT powered.

see this link for more info:

http://www.mp3car.com/the-faq-emporium/117895-faq-relays-how-they-work-and-how-to-wire-it-up.html

As you can see the terminal marked '30' is usually the positive feed from the battery and the terminal marked '87' is the switched output to the load (in this case the compressor clutch). To connect the battery supply directly to the compressor clutch you need to unplug the relay and bridge the terminals of the relay socket which correspond to terminals '30 and '87' of the relay. Hope this makes sense to you?

Without a safety pressure cut off the high side pressure could get high enough to damage the system and possibly cause injury to yourself. Thats why its handy to have a momentary switch for bridging the relay because it will cut the clutch supply as soon as you release the switch. I would never bridge the relay without a set of pressure guages connected unless it was just for a few seconds to check the operation of the clutch.

JJM on Thu July 28, 2011 9:44 PM

The compressor clutch not engaging is probably the least of your problems. Based on what you've described, everything has been done wrong. Improper flushing techniques, lack of a proper gauge set, no vacuum pulled, absence of a HPCO, oil level guessing,

If you want to engage the clutch all you have to do is disconnect the clutch and apply +12v fused directly to it. But how is this going to solve your problem?

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com

diyman on Mon August 01, 2011 2:18 PM

JJM, thanks for your comments, but if you look back to my previous threads, I had vacuum pulled, system has dual pressure cut off switch, and 4oz oil is the required amount for the system.

fisyyma, thanks for your description and link. I connected 12v to compressor clutch and it engaged and turns when engine is running (blows cool air for about 30 sec., then hot air). I connected 12v to condensor fan, the fan also turns. Cooling fan also turns a few minutes by itself after engine is hot and shut off. I remembered both fans turn as soon as I turn on my A/C before retrofit, but they won't turn any more right after retrofit. The pressure reading on both low and high sides are '0' even after charging 34oz of R134a into system (system requires 32 - 34 oz of R12 and 4 oz oil, I charged 24oz first and see no cooling air, then continue to charge 1-2 oz at a time to 34 oz). I also make sure system has no leak (hold vacuum overnight) before charging. It looks like clutch doesn't engage and condensor fan doesn't turn are all because of dual pressure cut off switch since reading are '0'. Why reading are still '0' after charging 34oz of R134a? What could the problem and what should I check next?

DaveMcKenz on Mon August 01, 2011 5:31 PM

It sounds like your gauge hose connector is not pressing the shrader valve stem when you hook up the gauges. I don't know how to fix that without getting a different connector or adapter.
Good luck,
Dave

mk378 on Mon August 01, 2011 5:32 PM

You are reading zero because the gauge hoses are not coupling to the car properly. Did you use the cheesy aluminum adapters from the retrofit kit (of course). I'm also betting on Harbor Freight gauges.

You should quit jumping stuff before it makes the situation worse. Get some real pressure readings. Troubleshoot the electrical system by probing, not jumping.

diyman on Mon August 01, 2011 5:42 PM

Yes, I am using Harbor Freight gauage and it is new. I make sure it connects properly when I hooked it up. Jumping wire is just making sure they are all working and temporary for diagonsis only.

mk378 on Mon August 01, 2011 5:46 PM

As you read zero with the engine off you need to resolve that first. You don't need to start it or jump anything.

diyman on Mon August 01, 2011 6:02 PM

Yes, that is what I am asking. Could it be possible the system has full of charged with refrigerant and oil, but reading is still '0' assuming no leaking in system? What should I check or fix at this point?

mk378 on Mon August 01, 2011 6:13 PM

No if you have a full charge the pressure can't be zero. You should read about 100 on both sides with the engine off. Your gauge set needs to be replaced and possibly the adapters on the car. Seriously, spend twice as much on the most basic Mastercool set and have something that is infinitely better value because it actually works.

Or there is the not so remote possibility that it actually did leak down to zero, because of all that damn jumping the compressor opened the relief valve.

Edited: Mon August 01, 2011 at 6:16 PM by mk378

TRB on Mon August 01, 2011 9:20 PM

Quote
Originally posted by: mk378
No if you have a full charge the pressure can't be zero. You should read about 100 on both sides with the engine off. Your gauge set needs to be replaced and possibly the adapters on the car. Seriously, spend twice as much on the most basic Mastercool set and have something that is infinitely better value because it actually works.



Or there is the not so remote possibility that it actually did leak down to zero, because of all that damn jumping the compressor opened the relief valve.

and or harbor freight gauge set.



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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

JJM on Tue August 02, 2011 12:16 AM

Indeed that's probably your problem right there... those Harbor Freight gauges.

Last thing a DIY'er should skimp on is tools... bad enough trying to learn, only to be frustrated by tools that don't do the job and then ending up defeated and taking it to a pro.

Site sponsor has reasonably priced gauge sets. Even the entry level sets are pro quality.

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com