tac40
Elite Explorer
- Joined
- July 15, 2013
- Messages
- 45
- Reaction score
- 0
- Year, Model & Trim Level
- '97 Ford Explorer Sport
Hi again,
Am chasing a frustrating problem on a 97 4.0 SOHC 2WD explorer. (manual, *not* climate-control version). Bought it used with 161K miles and a blown trans. After fixing the trans, I had several A/C-related items to address, and thanks to the wealth of info from the many folks on the forum, I have several of them resolved.
The compressor, evaporator, & filter/drier had been recently replaced before I bought it. This vehicle also had the typical broken blend-door and failed vacuum reservoir/globe, and a burned out temperature control pot. I replaced them and now all the controls work properly, air flows from the expected vents at the expected temps, etc.
The one thing that I still haven't found the cause of is why the compressor turns off after about 30-40 minutes of driving. It'll virtually *never* fail if idling in traffic or idling in my driveway while I'm hunting for the cause. I've already tried jumping out the low & hi pressure switches, and the WOT relay.
Jumping over the pressure switches made no difference, but today when it shut off, I jumpered over the WOT relay and it turned back on. I replaced the relay but it didn't help. I still haven't been able to locate whatever triggers that relay. I've read that there's a vacuum switch in or around the intake but I don't see it. Anyway, after jumpering the relay and having the clutch re-engage, I thought what the heck, I'll just leave the jumper in.
Went for a test drive but no-joy. After about 35 minutes it disengaged again. I stopped and jumpered over the lo and hi-pressure switches again but it wouldn't turn back on. I pulled the #18 15A fuse and checked it but it was fine. After turning the vehicle off for a few minutes, it was fine for about another hour.
I've looked at the airgap on the clutch and it's very minimal. The compressor doesn't make any funky noises, nor is the system freezing up. The A/C works very well so long as the compressor is spinning.
So now I'm wondering if the clutch is actually losing 12v when it drops out, and if so, why? It doesn't cycle on-and-off at an a idle, nor can I seem to induce it to shut off by driving it a certain way or over bumpy roads or by jiggling wiring harnesses, connectors, fuses, relays, etc.... It just quits after 30-40 minutes. Very frustrating.
Any suggestions on how to troubleshoot this further? Most of what I've been trying isn't yielding anything positive. Any info is sincerely appreciated. Thanks!
--mike
Am chasing a frustrating problem on a 97 4.0 SOHC 2WD explorer. (manual, *not* climate-control version). Bought it used with 161K miles and a blown trans. After fixing the trans, I had several A/C-related items to address, and thanks to the wealth of info from the many folks on the forum, I have several of them resolved.
The compressor, evaporator, & filter/drier had been recently replaced before I bought it. This vehicle also had the typical broken blend-door and failed vacuum reservoir/globe, and a burned out temperature control pot. I replaced them and now all the controls work properly, air flows from the expected vents at the expected temps, etc.
The one thing that I still haven't found the cause of is why the compressor turns off after about 30-40 minutes of driving. It'll virtually *never* fail if idling in traffic or idling in my driveway while I'm hunting for the cause. I've already tried jumping out the low & hi pressure switches, and the WOT relay.
Jumping over the pressure switches made no difference, but today when it shut off, I jumpered over the WOT relay and it turned back on. I replaced the relay but it didn't help. I still haven't been able to locate whatever triggers that relay. I've read that there's a vacuum switch in or around the intake but I don't see it. Anyway, after jumpering the relay and having the clutch re-engage, I thought what the heck, I'll just leave the jumper in.
Went for a test drive but no-joy. After about 35 minutes it disengaged again. I stopped and jumpered over the lo and hi-pressure switches again but it wouldn't turn back on. I pulled the #18 15A fuse and checked it but it was fine. After turning the vehicle off for a few minutes, it was fine for about another hour.
I've looked at the airgap on the clutch and it's very minimal. The compressor doesn't make any funky noises, nor is the system freezing up. The A/C works very well so long as the compressor is spinning.
So now I'm wondering if the clutch is actually losing 12v when it drops out, and if so, why? It doesn't cycle on-and-off at an a idle, nor can I seem to induce it to shut off by driving it a certain way or over bumpy roads or by jiggling wiring harnesses, connectors, fuses, relays, etc.... It just quits after 30-40 minutes. Very frustrating.
Any suggestions on how to troubleshoot this further? Most of what I've been trying isn't yielding anything positive. Any info is sincerely appreciated. Thanks!
--mike
