Engine Size: 1.6
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 50
Pressure High: 325
I've been fighting this a/c issue for a few years now. Here's a link to my last set of efforts:
Short version of what I've done prior to today is replaced the compressor, condenser fan, receiver/drier, and straightened the condenser fins. Evacuated/recharged about 10 times. No matter what I did, pressures were 30-45/275-350 @ 95-110 degrees ambient. Vent temps were 40 when driving and shot up to 70 when sitting idle in 110 degree ambient. Compressor also cycled about every 3-5 seconds when idle in the 110 ambient.
Fast forward to today... I replaced the expansion valve and my pressures are 50/325 @ 95 degree ambient. When driving, vent temps are 40. When sitting idle vent temps are 60. Basically, not much change.
It still seems I have a blockage on the high side, but when I had the condenser out, I disconnected the lines at the compressor and blew 100psi compressed air on both lines. There was no back pressure on the low side and very slight back pressure on the high side. I also blew air through the condenser and there was no back pressure there either. Low pressure air passed freely though the expansion valve.
I'm out of ideas for things to fix and replace. Anyone have any ideas before I throw in the towel on this one?
Edited: Sat March 22, 2008 at 8:17 PM by DaveInPhx
Was there ever an issue with debris in the system? If so was the condenser replaced?
Just a hint, are you sure the fan(s) are blowing in the right direction??
Freedoms just another word for nothing left to lose
When confronted with a problem such as this....it is always best to return to a basic starting point.
No one wishes to do repairs more than once...but it is essential that a base line be set. Suggest to recover the refrigerant....remove the evap/TXV and through flush the evap. Add back the required amount of lubricant to the evap at this time....cap suction/liquid lines and reinstall. The drier should be replaced...it is not known how much lubricant is maintained in this unit, or if there is a restriction. When arriving at a lubricant recharge...subtract app 2 oz for the compressor charge.
Insure that the TXV inlet is clean and there is no evidence of debris.
Re-connect all connections and evac the system. At your temps....30-45 minutes should be sufficient. Insure that the system is properly recharged.....unfortunately the use of cans, large or small, and pressures is not a good indication of a fully charged system. The use of proper recharge equipment is suggest.
Once the system is operation....allow for app 5 minutes for the system to stabilize....then perform some basic test on the condenser.
Use the follow conditions....max cool...high blower....engine at idle.....door open. Using a good temperature measurement tool.....n cot an infrared....something that actually make a mechanical contact with the component being tested. If this is not available...Sears sells a 'good' multimeter with a temp probe for app $30.00. Test the condenser inlet (discharge) and the outlet (liquid) prior to the rec/drier....a good temp drop should be app 20-25 degrees. If this temp drop is much greater....the condenser is probably restricted.....if less....there is a heat transfer problem....Chick stated...check the fans....a great place to start.
Insure that the rad and other cooling system components are functioning as they should.
Test ambient temp (air temp) about 12 inches in front of the condenser...and then test vent temps at the center outlet.....look for a temp drop....min 25 degrees....if less...there is a good possibility of blend door/heater valve problems....it is doubtful that this is the problem.
The statement that the system cycles rapidly....this is controlled by a sensor located within the evap itself...insure that this probe is in the correct position.
Blowing air thru a condenser is not a valid test to determine a restriction. Best method I know is temp drop.
The most important of any ac diagnosis is to know if the system is completely and properly recharged.
From your post...an agreement is that there is a restriction.....history would lead to the condenser...esp if the system suffered a catastrophic compressor failure.....the next would be the rec/drier...possible over charge of lubricant....may test this first....see if the drier is the same temp...top to bottom....if cooler on the bottom....there is a restriction...probably lubricant overcharge.
Good luck with the repairs...
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
That cycling is why you have very poor cooling at idle. The compressor should not cycle at idle unless the vent temps are down to 40, which is not going to happen in 110 degree weather. There are 2 abnormal conditions that might cause it to. If the high side goes above about 450 the pressure switch will cut it off. If the engine is idling too slow the computer will drop out the compressor to prevent stalling. You might want to hook up a good tachometer (don't trust the one on the dash) and see if the idle speed is right, I think it should be 800 rpm with the compressor on.
There is only one condenser fan on this car. I replaced the OEM with a higher rated fan which seemed to help very little with the cycling at idle.
The cycling is due to high head pressure. I'm sure of that based on gauge readings when it kicks out.
You may be on to something with the lubricant. For a time there I would add an ounce or two each time I had the system open just to make sure I had enough in there and when I changed the drier I added 1/2 the amount called for. I didn't know having too much would cause restriction. I was under the impression that it would affect cooling, but I hadn't read anything about it causing a restriction in the system. I can certainly see how excessive lubricant could be the cause if it accumulates in the drier, though.
Ok, so how do I go about getting all the lubricant out and starting over?
Assuming the fans are good and blowing in the correct direction and the system is charged correctly, flush the system and replace the condenser and receiver dryer.
Flushing the system will ensure you are starting out with a clean system (no oil), ensuring the correct amount of oil will be added back to the system. The culprit here most likely is the condenser, which is why the system is "cycling" at 110F... not really cycling in the traditional sense, but the HPCO cutting the compressor preventing something from blowing up.
High on both sides, so I have to ask:
(1) Are you charging into a vacuum, like are you evacuating the system first?
(2) Are you adding too much refrigerant?
You may want to bite the bullet and take it in to sponsor, Arizona Mobile Air, since you're in Phoenix....AC is not exactly a "vanity option" here...
Edited: Sun March 23, 2008 at 3:48 PM by Cussboy
Too much oil is bad. Less room for refrigerant then. When the condenser starts to fill up with liquid (oil or refrigerant) it's capacity is impaired and you will have excessive pressure. So you should clear all the oil out and start over.
Ok, I flushed the system and changed the drier. I started out with the specified amount of oil and refrigerant charge. Vent temps were good at about 40 degrees, but pressures were 35/325. I backed out about 1/2 of the refrigerant until the vents warmed up and then added refrigerant back until I ended up with the specs below (it's about 4oz shy of spec).
95 degree ambient
@ 800 rpm (idle) pressures are 37/205 with 49 degree vent temps
@1500 rpm pressures are 24/254 with 44 degree vent temps.
Driving at 40mph vent temps get down around 38.
Keep in mind, the first two readings are with a high velocity fan blowing on the font of the car. When I turned the fan off, the high side went up about 30psi and the low side went up about 10psi.
Condenser temp readings vary from around 190 on the inlet down to 170 on the outlet (Fluke meter with temp probe). Temps seem high to me, but there is definitely heat transfer taking place.
I think I can live with it as it is, but it seems it's still not 100% yet.
I'd agree with TRB that the next thing would be a new condenser, as long as you're sure the fan is OK (maybe it's a aftermarket unit with less performance than OEM?) Condenser could be partly blocked inside. Anyway having to undercharge to keep the high side down means that your condenser is one way or another not up to the job. Why did the compressor need replacing in the first place? Did the original one go to pieces?
The clutch crapped out and the compressor was pretty old so I decided to go ahead and replace the whole thing.
I really don't want to replace the condenser. I guess I'll see how it does this summer and if it's not up to the task, the condenser will be next.
Thanks to everyone for their help!
change it now, or you'll be changing the compressor again..Just a heads up...
You have to to run it with the full charge to make sure the proper oiling of the compressor..
Freedoms just another word for nothing left to lose
Edited: Tue March 25, 2008 at 8:52 PM by Chick
Just a reminder, these newer style condensers can still have passages blocked while there is flow present. Thus the reason I asked before if there was ever debris is this system.
did you fix the problem?
i have a 97 civic and i am in the same boat
but i think its just too hot for it.
at 95 * ambient im at 25/275 at 1500 rpm but i do get nice cold air.
i am thinking about replacing my condensor since its pretty beat from rocks and bugs
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