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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / August 2006Why would AC only work when foot is on gas?
Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, it gets very hot when the car is idling. My first thought is that the engine is getting so hot, I need to be moving to have the additional air cooling. However, I discovered today, the AC work fine when I'm sitting at a stop light if I just put the vehicle in neutral and give it gas. Strangely enough though, the 1995 doesn't do that. Sitting idle in the sun it cools so well that after 5-10 minutes you have turn down the AC. Any ideas why the '97 is having this problem? Is it an AC problem, AC clutch? harmonic balancer, or just a design flaw? Works great on the freeway, but in city traffic in Dallas I'm quickly getting up to 100+. many thanks for any suggestions! David maybe you have a power problem bring it in to autozone and they can test for free! > Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 > works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, [quoted text clipped - 12 lines] > many thanks for any suggestions! > David > Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 > works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, [quoted text clipped - 3 lines] > sitting at a stop light if I just put the vehicle in neutral and give > it gas. I want to be sure I understand what is happening here. At an idle is the compressor turning? If the compressor is turning at idle it sounds like the AC system needs a recharge. > Strangely enough though, the 1995 doesn't do that. Sitting > idle in the sun it cools so well that after 5-10 minutes you have turn [quoted text clipped - 6 lines] > many thanks for any suggestions! > David >> Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 >> works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, [quoted text clipped - 9 lines] >If the compressor is turning at idle it sounds like the AC system needs >a recharge. If so it would cycle off when reved up. Don www.donsautomotive.com >> Strangely enough though, the 1995 doesn't do that. Sitting >> idle in the sun it cools so well that after 5-10 minutes you have turn [quoted text clipped - 6 lines] >> many thanks for any suggestions! >> David >Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 >works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, [quoted text clipped - 12 lines] >many thanks for any suggestions! >David A weak compressor will work half-assed at high rpm and cool little or not at all at low rpm. This can easily be verified with gauges. You might see 70-80 PSI low side, maybe 130 high side at idle. Should be more like 30/200 but this is dependent on MANY factors. Don www.donsautomotive.com > Our family has two Isuzu Rodeos, a 1995 and a 1997. The AC on the 1995 > works great. the 1997 stinks. On the '97 Rodeo when I'm sitting still, [quoted text clipped - 12 lines] > many thanks for any suggestions! > David Usually poor cooling at idle that is solved by revving up the engine is either too little air-flow over the condensor due to a weak engine-driven fan, a compressor that has a dead cylinder or two (usually due to broken reed valves) and is down on capacity, or low refrigerant charge. Trying to summarize the questions from all: 1. I'm not sure if its not turning at idle. The fan is running, but its just circulating air, there is no cold air coming in. 2. When I rev the gas, then magically cool air comes in. So, when I'm at a stop light and want to stay cool I rev the engine, and everyone wonders why a guy in a 1997 rodeo wants to race them. (hey, at least One other note - I just had my AC replaced. The folks have a 1 year warranty. I've heard really good things about them from other people that have used them. When I first got my car back it worked great for about 3 weeks then the AC sort of died, I took it back and they fixed it, but now I have the no air at idle problem. > Trying to summarize the questions from all: > [quoted text clipped - 12 lines] > about 3 weeks then the AC sort of died, I took it back and they fixed > it, but now I have the no air at idle problem. I wish I had specific experience with the 97 Rodeo, but some Imports use an A/C idle up solenoid that increases airflow through the throttlebody to slightly raise idle speed. Dashpots on the throttle have also been employed. Typical Import A/C logic is to disengage the compressor if engine RPM is below a certain point. If the idle up system was to fail, your compressor would not engage at standard hot idle speed. It would kick in as soon as you gave the slightest goose to the gas pedal. I have noticed this system disappearing on OBDII vehicles, perhaps because they employ step adjustable feedback idle controls already. Perhaps your Rodeo still employs an old style A/C idle up system. Toyota MDT in MO > Trying to summarize the questions from all: > > 1. I'm not sure if its not turning at idle. The fan is running, but its > just circulating air, there is no cold air coming in. With the AC on open the hood and look at the compressor. > 2. When I rev the gas, then magically cool air comes in. When you rev the engine is there a click and slight lugging of the engine as the compressor clutch engages? > So, when I'm at a stop light and want to stay cool I rev the engine, > and everyone wonders why a guy in a 1997 rodeo wants to race them. [quoted text clipped - 5 lines] > about 3 weeks then the AC sort of died, I took it back and they fixed > it, but now I have the no air at idle problem. Take it back explain the problem and get it fixed under warranty. |
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