Model: Eclipse GS
Refrigerant Type: R134A
Country of Origin: United States
I need help diagnosing the issue with my air conditioning: it seems to be running only in the morning on cold start and stops after about 20 minutes. On hot days, after work (car being in the sun the whole day), the cooling does not start at all and it blows hot air. After it works for a while, I know also for sure when it stops not only by the fact that it does not blow cold air anymore, but also I can sense a weird smell coming from the vents. Speed does not seem to matter either, it still does not work on the highway at 65 mph, thought it would improve the air flow and the cooling, but it does not.
Tried adding a little bit of refrigerant and dye, but did not help, so I decided to get some gauges and an UV light and did some diagnostics myself. Will need some help to interpret the results. Here is what I found:
1) UV light revealed nothing other than one leak at the low side shrader valve. I thought initially that it was because dye was added through it, but I am positive now that it leaks: 3 times already when I opened the plastic cap I heard it hissing and also, after I removed the low side gauge, I visually saw it leaking slowly inside. Tried to pull it a little bit with a pliers, and the leak seemed to improve, hope the cap will keep the refrigerant in until I change the valve.
2) Test was done today at around 80-82 F outside temperature. Static pressure read 94 psi in both sides.
3) Started the car on max AC, max fan recirculating and windows open and let it idle for about 5 minutes. AC was ice cold, low side pipe cold:
- Low side: 32 psi. High side: 185 psi.
4) At 1500 rpm, two measurements, AC still ice cold, low side pipe still cold:
- Low side: 20 psi. High side: 250 psi;
- Low side: 40 psi. High side: 200 psi.
5) At 2000 rpm, AC still ice cold, low side pipe still cold:
- Low side 15 psi. High side: 275 psi
6) Back at idle, AC starts warming up, low side pipe warming as well (I noticed that when the AC is not working, the low side pipe becomes warm, even hot after a while on the highway), compressor clutch NOT engaged:
- Low side: 56 psi. High side: 130 psi
- Low side: 68 psi. High side: 125 psi.
7) Brought it back at 1500 rpm, started working again:
- Low side: 20-40 psi. High side: 200-225 psi
8) Back at idle, still working:
- Low side: 30 psi. High side: 180 psi.
So, outside of the low side valve leak, when the AC is blowing warm/hot air, the compressor is not turning and the low side pressure seems high and the high side seems low. Also, the low side pipe becomes warm or even hot after a while.
Any suggestions on the cause of intermitent cooling (mostly works well after starting the car, and stops after a while, few times coming back on, but not always)? Thank you!
When it is not cooling, place a test light at the compressor terminals to find out if 1 volts DC is getting to the clutch.
Clutch not engaging consistently when hot usually is because the gap between the pulley and the clutch plate is too large. If you can do so safely, engine running and A/C button still pressed, tap the clutch plate with a suitable tool after it stops. If it pulls in and cools again for a while, you need to adjust the gap.
Thank you. I tried today but wasn't able to make it not work, I'll wait for a hotter day and let you know.
Edited: Sat May 12, 2012 at 6:10 PM by dannysporea
I was finally able to do more testing, as suggested: when the compressor is not engaged, I measured 13-14 V at the terminal, same as when it is working.
Tried to tap the plate as well when not working, but without success, nothing happens.
Does the compressor always need to be turning when the voltage is applied to the terminal, or there could be some other control in addition to this voltage that keeps it from engaging?
Like a faulty temperature or pressure sensor? Any other suggestions I could try?
The behaviour described above is still consistent, it always works immediately after the car is started, and stops after a while...
I also measured the pressures again when not working after a longer trip, and it reads 110 PSI on the low side and 125 PSI on the high side.
Edited: Thu May 31, 2012 at 7:36 PM by dannysporea
Some compressors have an overtemperature sensor on the compressor in series with the clutch wire. Also make sure the compressor is grounded.
Compressor should be engaged all the time the wire has power, unless there is something in series with the ground side.
On a hot day, warm up the engine, then with the engine OFF, disconnect compressor wire and jump it to the battery. Compressor should pull in. Now close the hood and walk away for about 15 minutes. Come back and disconnect the jumper and re-jump it and see if the compressor pulls in again. Also sparks should fly when you connect the wire, showing that the circuit is complete. If it doesn't pull in, since the engine is OFF it is safe to reach in with your hand and press on the clutch plate, see if that makes it pull in. (Never run the engine with the compressor jumped.)
Thank you for the suggestions, I will try this test. While waiting for another hot day, I found the service manual of the car. It seems that after the A/C terminal, there is an "A/C Refrigerant Temperature Sensor" in series with the magnetic clutch. Could this one might be broken? I am thinking of trying to short it, so it will be always on, regardless of the sensor reading. Do you think this can be a problem? The manual reads: ON -> OFF at 155 deg C and OFF -> ON at 125 deg C. If the sensor is broken and I try to replace it, does this open the refrigerant circuit? The manual is not clear how this sensor is located inside the compressor, if it is in direct contact with the refrigerant (which would open the circuit if I remove it) or not.
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