A/C not working. Fans still blow air. ??? [Archive] - GrandAmGT.com Forum

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mightypan42
09-16-2004, 09:55 AM
As it says... the fans are blowing fine, just not cold air. This is when the knob's turned to Max A/C and the A/C button pushed. Any ideas?

abusedgt97
09-16-2004, 12:33 PM
Is the compressor making any funny noises, also is the system charged?

Matt95GT
09-16-2004, 01:01 PM
Is the compressor running? (look/listen) The A/C will still blow air thru the vents if the compressor is running or not.

If the system does not have enough refridgerant the compressor will not engage.

mightypan42
09-16-2004, 01:31 PM
I didn't hear the compressor, so I don't think it was on. How do I check the refrigerant?

AleroME
09-16-2004, 07:22 PM
I didn't hear the compressor, so I don't think it was on. How do I check the refrigerant?

Only way to self-check is to buy some AC gauges to read the pressure off the high and low side lines.

MagusXIII
09-16-2004, 07:53 PM
Only way to self-check is to buy some AC gauges to read the pressure off the high and low side lines.
If the refrigerant level is low, you will not get a proper reading on both the suction and discharge sides due to the fact that the compressor is not engaging.

Mightypan, like others said, observe for compressor engagement. To do this, look at the very front of the pulley for the compressor, which is the magnetic clutch. Observe it while the system is on vent or heater...or even off. The front of the pulley will not spin. Now...turn the system on. if the system is working, you will see the front of the pulley spin with the rest of the pulley itself.

Now...if the clutch will not spin with the pulley, it could be two things. Either low R134a levels as matt95gt said or worse, a bad clutch field coil. If the field coil is bad, it will not generate enough of a magnetic pull to force the clutch to engage the pulley and thus spin the compressor. If the clutch does not engage, you will need to find the plug that leads from the receiver/dryer or accumulator (sorry, I know jack about the GM V5 compressor and subsequent AC system components) and disconnect it. Then two pins will need to be jumpered together. This will force compressor engagement regardless of refrigerant level. If the clutch now spins....fine. You found your problem. Shut the system off quickly as extended compressor operation w/o sufficient R134a in the system will burn out the compressor. If the clutch does not spin, check all fuses pertaining to the AC and if they are good, take it to a shop and tell them you suspect the clutch field coil is bad. Of course, if you know a friend that does AC work, that is even better.

If the clutch will turn when the two pins on the pressure sensor harness are shorted, connect the R134a can to a charging hose or, if you have a manifold gauge set, connect it to the center yellow hose and open up the low side valve on the gauge set. Keeping the aforementioned connector jumpered, open the R134a can (note that both bulk cylinders and 12oz cans will connect to a charging hose on a manifold gauge set or a basic DIY charging setup) and allow the compressor to draw in the refrigerant. Do not overcharge the system or else you will not get sufficient cooling. This is due to such a high amount of R134a in the system as to not even allow proper expansion in the system.

When using a manifold gauge, be sure to get from a service manual the proper engine RPM in which all pressures are to be taken. My ZX2's FS10 compressor requires all readings at any temperature to be taken at 1500rpm. Make note of what your system pressures are to be between when at a certain temperature while at the specified RPM.

If the clutch turns when you first turn on the system and you still get hot air, check the orifice tube. This will mean you have to open up the system and if you do that AND the orifice tube is bad, may as well replace the receiver-dryer/accumulator while you are at it. Better yet, it may even be a good idea to replace that if you open the system period.

Anyway, the first thing is to check for compressor operation and let us know. Other members will be more than helpful in telling you how to bypass the low pressure cutoff. Heh, if you still had the GM R4 compressor, I could help you more! :D

IMO, R134a is junk. My ZX2 lost its refrigerant back in 2002 and I had to recharge it. I mistakenly trusted a cheap suction pressure gauge and even though I got it to a suction pressure of 40psi, in reality I was over 70PSI and...my high side (discharge) pressure was over 350psi!!!!!! A good manifold gauge set allowed me to correct the pressures. But I have always felt that R134a systems are more leak-prone than good old R12. And...I have a hard time believing R12 is such an environmental danger and that it is destroying the ozone layer several miles above the earth when r12, as well as all halogens, refrigerants, and CFC compounds are...heavier than air??? :rolleyes: But...that is another topic entirely...


Don

Silverbird
09-16-2004, 08:40 PM
^^^^^ Excellent Reply :thumbs: :thumbs: :thumbs:

Sounds like you've got some HVAC experience.

02andahalfgt
09-16-2004, 09:04 PM
Don

Damn man, you know your sh!t!!!! It's gonna be nice having you around. :ec:

mightypan42
09-17-2004, 06:39 AM
Thanks. I'll check that out tonight.

jamcllw
09-17-2004, 07:37 AM
I had a small 10 amp fuse blown in the fuse box in the engine bay that was causing my ac to not blow cold. Replaced it and it has been fine ever since.

MagusXIII
09-17-2004, 05:05 PM
^^^^^ Excellent Reply :thumbs: :thumbs: :thumbs:

Sounds like you've got some HVAC experience.
Thank you. Actually, my HVAC experience is limited. I basically am only relaying my experiences. Aside from that, I do not consider myself an HVAC expert by any means.

I do remember some stuff from a couple years ago when I was starting to study for my Section 609 test. That would give me the legal authority to purchase R12...


Don