A/C Problem

**romulo13** · 08-05-2006, 03:06 PM

My a/c runs well for twenty to thirty minutes, then it blows at less than half power. If I cut the a/c off and keep driving for 10 minutes it will come back on to full power for another 20 or 30 minutes. It happened once before while my car was under warranty and they fixed it. The guy said that it was a sensor that went bad. Now the car is not under warranty and I have looked on the internet for a/c sensors, where they are and how to replace, but I have had no luck. Anyone have any ideas?

02 WS6

**2001NBMZ28** · 08-05-2006, 03:15 PM

Sounds like the charge is just low - evaporator is freezing. If it was the low/high pressure sensor the compressor wouldn't even come on. Does the fan speed change or just the airflow?

**romulo13** · 08-05-2006, 03:44 PM

Which fan do you mean? The radiator fan or does the a/c have it own fan? The airflow gets weak, but the air that comes out is always cold.

**2001NBMZ28** · 08-05-2006, 04:27 PM

The fan in the blower box on the passenger side inside the car....once it freezes you're basically trying to blow air through/around an ice cube. See if you can get a "free AC check" somewhere, around here there are signs all over the place. If it's just low you can buy a recharge kit.

**romulo13** · 08-05-2006, 04:59 PM

I will do that, thanks for all the help.

**02z28ls1** · 08-05-2006, 05:29 PM

Are you leaving it on MAX A/C ? It will freeze up under certain conditions-cut back to regular setting after a couple of minutes.

**6spd** · 08-14-2006, 07:56 PM

Does Max A/c use more gas?
What exactly does the MAX setting do?
I never used it because I figured it was harder on the system.

**Spitfire** · 08-15-2006, 01:35 PM

MAX AC only recirculates the air you are cooling in the cabin. So, it's cooling cold air even colder.

**02z28ls1** · 08-15-2006, 03:27 PM

True -on MAX it is only recirculating cabin air-regular setting cools outside air. Upon reading his post again I don't think that's the problem anymore. I haven't seen any one doing "free" A/C checks around here. But maybe $20 -$30 ones-then add freon -you'll probably be good to go. The sensors being referred to must be the high and low pressure sensors-they are located in the A/C lines and will have 2 wire connectors to them. They will be located in "T" fittings in the small (high) and big (low) diameter A/C lines. Maybe have them replaced if the freon charge is OK to see if that cures the problem.

I just had to use that icon--it doesn't mean anything about this thread-lol

**romulo13** · 08-16-2006, 09:58 AM

Thanks for the help on locating the sensors. Anyone know if these a/c shops can check both freon and sensors, because I don't know of a trustworthy a/c shop. They might just say I need freon, but freon doesn't come and go does it? If I don't have it, I don't have it. Will it come out for 30 minutes and then disappear? All I do is shut the a/c off for 10 minutes and it is good as new.
I live in Southeast Houston, anyone know a reputable shop?

WS6BIRD · 08-19-2006, 05:31 PM

sounds like the evporator is freezzing. if it blows cold after you turn it off. the low pressure sensor is designed to cut the comperssor off to prevent it from freezing up. sounds like that is what the dealer replaced.

**gnomee** · 08-19-2006, 06:14 PM

You have said it blows weaker but it is still cold. ARe you sure it is not blowing down by your feet a little more and less thru the vents. The reason I ask is, the part of our system that directs air from the floor up to the vents is vaccum operated. At certain RPMS mine blows weaker and then starts blowing hard again. Not sure if it is this but worth a shot. Just to the right of the PCM on the passenger side under the hood there is a vacum line with a T on it. Mine melted twice and caused me all kinds of weird issues like what you describe. I bought a new one and coated it in 2 ton epoxy and it has not melted again.

**hgsaint** · 08-20-2006, 06:07 AM

I had a similar problem with a 1994 1500 and the problem was the low pressure switch on the dryer. I think this is your problem.

**02z28ls1** · 08-20-2006, 06:42 PM

Some cars seem to lose freon without being able to accurately diagnose a leak. So yes it could be a low charge-need to have the gauges hooked up to tell. And yeah-I hate to say it but there are some less than honorable mechanics out there. Can't help you there.
But I think it is probably the sensors as i stated before. When it is not working right you need to pull over and see if the compressor is engaging at that point or not. That would help narrow it down. If the compressor is not engaging then it is a sensor or electrical issue. If the compressor is still cycling normally then it may be a vacuum switch problem directing the air (as someone else was tryingto point out)to the lower vents or changing the air doors in some manner to prevent full air flow.