runfastdontstop
New Member
- Joined
- July 3, 2010
- Messages
- 1
- Reaction score
- 0
- City, State
- Denver, CO
- Year, Model & Trim Level
- '97 Sport 4.0L SOHC
I had some A/C problems a while ago - basically, the compressor clutch was cycling rapidly (2-3 seconds) at idle before it eventually died completely and the compressor didn't engage at all. After taking it to Midas and having the system recharged, it still didn't work so they offered to replace my compressor for the low-low price of $1500. I ended up doing some homework on these forums and diagnosed that it was the low pressure switch that had gone bad (jumped it and the compressor engaged).
I took it to a more trusted mechanic and got everything fixed. They replaced the accumulator with the low pressure switch, as well as the A/C cycle switch and the IAC Valve. They explained the initial rapid cycling problem was because when the A/C is turned on, the idle rpm should increase slightly to account for the additional load of the compressor. Sure enough, after that, when I turned on the A/C the idle rpm increased 100 rpm or so, which it had not done before. So everything worked great... for a while.
A few months later, the idle rpm no longer increased when I switched on the A/C. So now we are back to having the compressor cycle rapidly when I'm idling. I'm noticing that the truck is idling around 500 rpm, then the compressor engages and the rpm's drop below 500, the computer notices the idle is too low so it disengages the compressor... then repeat. If I tap the gas slightly to raise the rpm's, the compressor stays engaged just fine. By the way, the A/C still blows ice cold.
So do you guys think that either the new IAC valve or A/C cycle switch could have gone bad prematurely, and that replacing the right one would fix my problem? I would have taken it back to the original mechanic for a warranty check if I hadn't since moved across the country...
I took it to a more trusted mechanic and got everything fixed. They replaced the accumulator with the low pressure switch, as well as the A/C cycle switch and the IAC Valve. They explained the initial rapid cycling problem was because when the A/C is turned on, the idle rpm should increase slightly to account for the additional load of the compressor. Sure enough, after that, when I turned on the A/C the idle rpm increased 100 rpm or so, which it had not done before. So everything worked great... for a while.
A few months later, the idle rpm no longer increased when I switched on the A/C. So now we are back to having the compressor cycle rapidly when I'm idling. I'm noticing that the truck is idling around 500 rpm, then the compressor engages and the rpm's drop below 500, the computer notices the idle is too low so it disengages the compressor... then repeat. If I tap the gas slightly to raise the rpm's, the compressor stays engaged just fine. By the way, the A/C still blows ice cold.
So do you guys think that either the new IAC valve or A/C cycle switch could have gone bad prematurely, and that replacing the right one would fix my problem? I would have taken it back to the original mechanic for a warranty check if I hadn't since moved across the country...
