It sounds like the expansion valve isn’t working properly.
Tester
1 Like
I hope not, but you may be right.Would that explain the better performance at higher speed/RPM? It still may be an airflow issue, though because If I drive non stop for a few minutes even at low speeds it cools down considerably.
All car air conditioners perform better at an elevated speed/RPM. If it isn’t broke, don’t fix it.
2 Likes
Someone suggesting spraying water on the condenser while the AC is on. I did that and the vent temp dropped 5-6 degrees. It obviously cooled it down, but what does it mean? Weak fans? I know AC performance improves while driving as opposed to idling, but the temperature increases up to 10 degrees when I’m stuck in heavy traffic and the car won’t cool down until I drive steadily for a few minutes.
Water on the condenser has a great cooling affect, I would have expected a greater drop in temperature. On the other hand 52 degrees at idle on a 95 degree day is not bad. You have to consider the ambient temperature in traffic is higher than the temperature posted by the news or weather report.
1 Like
Well, I just sprayed a little, then got back in the car to check. I’m basing ambient temperature on my dash display which is usually a bit warmer than the weather says. At any rate, I’m sweating in my car and lots of people say their cars are much cooler in similar conditions. I’m really just trying to determine if my AC can be improved/repaired or if it’s just not that great. The vent temp will get closer to 60 degrees when the sun is out if I’m stopped in gear long enough and the cabin temp gets well into the 80’s. It’s barely better than having the windows down.
I’d find a good ac shop.
1 Like
That 150 is a bit low for the high side. It should be up in the 225 range. With elevated RPMs the high side will climb but the low side will also drop lower than 35 which would make that abnormal.
Look at the suction hose under the hood with the A/C running for a bit. If that suction line and accumulator is not sweating then there is a problem and while I hate to say it; may involve a low charge condition.
If things are right an A/C should not have a problem producing 40 degree air on a 100 degree day.
1 Like
I’ll check the pressures again. I didn’t pay much attention to them when I did the charge because I was more concerned with weighing the refrigerant. I’ll Check them at idle and 2000 RPM and report back.
When checking the pressures, the engine has to be at 2,000 RPM’s with a large fan blowing at the condenser.
Tester
1 Like
After connecting the gauges and before starting the engine or turning the A/C on make note of the static pressure. This is the system pressure on both high and low sides and which should be the same.
That number should be in the 115 to 120 PSI range. If it’s in the 100 or less range that would point to an undercharge; no matter what the stated quantity is.
The fender tag on my son’s 96 Camaro 3.8 states a refrigerant capacity of 9 ounces. No way is or has that ever worked.
I suppose the hood sticker can be wrong, then. There are also misprints in the manual-probably a GM/Toyota miscommunication. A low charge is one of the number one reasons for poor cooling at idle that improves while driving. Also, it was 72 and pouring rain today and there was still a 10-12 degree swing in vent temp, driving vs idle. Another thing, the AC doesn’t warm up as much or as fast when I’m in park as it does when I’m stopped at a light. The car also idles higher in park than it does stopped in drive. I’ll get some gauges and check static, and running pressures.
Refrigerant capacity is listed as 14.5 to 16.6 ounces in the service manual. Adding more won’t help, stay in the center, 15.5 ounces. If the suction line near the firewall is cold with the blower on high, there is sufficient refrigerant in the system.
1 Like
That’s what I thought. The manual I saw actually said 15.5 oz. The low pressure line feels like a glass of ice water. Would air in the system cause this particular problem? I did my best to vacuum the system and it held vacuum as well.
The low pressure line is the suction line.
Too much oil in the system can reduce performance, the oil mixes with the refrigerant and dilutes it. Many replacement compressors come loaded with enough oil for the entire system, the system should have been flush of debris and oil, if not you could have too much oil in the system.
1 Like
Would too much oil just reduce the cooling ability overall or would it explain the inability to cool only at idle like my situation? I told my mechanic the new compressor already contained 3oz of oil, but I don’t know what all he did exactly. He did add some (more) oil though because he asked me to bring him some. Also, with an almost max charge wouldn’t another ounce or two of oil result in pressures too high/overcharge?
My car has three fan relays. I don’t know which one is which, but if the high speed condenser fan relay is bad, that would explain a lot. How would I test them or know which one is which?
1 Like
Thanks, but I don’t have any of that testing stuff.