92 Volvo 740 AC Issues
#41
#43
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2Small2Fail (02-27-2021)
#45
#46
Only the 1991 940SE, which is really a turboed 960, had the ECC--mercifully no other 940 did. Small differences or not, that 760/960 ECC never seems to work right or be able to be repaired successfully... I had several 1991 SEs, and 760s and all the "luxury" ideas Volvo put in these cars were a major PIA!
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2Small2Fail (02-28-2021)
#47
I kept tracing the voltage back until I found the problem. And since this is a thread about the 1992 760 and mine is a 1990, I'm going to post my results with pics for anyone else who might run into the same problem. Turns out there is a relay behind the glove box, and although I didn't see any problems with the circuit board, the contacts were oxidized. Once cleaned up, the AC kicked on and works fine. I also took the time and lubed my blower motor (again). That squeal is ungodly! Anyway, thanks for the hints!
#49
Thanks for the professional tips. My 92 940 AC just blows hot air. I connect (+) battery power to compressor clutch black wire and it clicked which means the compressor is good. Next..
1. I will check if there is power to the socket of pressure sensor mounted on the drier.
2. If it has no power I will reflow solder to AC control unit.
3. If it has power, I will jump the connection to see if compressor engaged. If compressor engaged then I will change the pressure sensor on the drier
Does these make sense to you? Thank you
1. I will check if there is power to the socket of pressure sensor mounted on the drier.
2. If it has no power I will reflow solder to AC control unit.
3. If it has power, I will jump the connection to see if compressor engaged. If compressor engaged then I will change the pressure sensor on the drier
Does these make sense to you? Thank you
#50
Thanks for the professional tips. My 92 940 AC just blows hot air. I connect (+) battery power to compressor clutch black wire and it clicked which means the compressor is good. Next..
1. I will check if there is power to the socket of pressure sensor mounted on the drier.
2. If it has no power I will reflow solder to AC control unit.
3. If it has power, I will jump the connection to see if compressor engaged. If compressor engaged then I will change the pressure sensor on the drier
Does these make sense to you? Thank you
1. I will check if there is power to the socket of pressure sensor mounted on the drier.
2. If it has no power I will reflow solder to AC control unit.
3. If it has power, I will jump the connection to see if compressor engaged. If compressor engaged then I will change the pressure sensor on the drier
Does these make sense to you? Thank you
The following users liked this post:
92 Volvo 940 (08-09-2022)
#51
Hi I thought I'd ask on this thread before making a new one, same exact car. I unplugged the low pressure sensor and tested at the plug. I have power to one lead of the plug at the low pressure sensor when the climate control is engaged. I jumped the other lead to the positive end of the battery and the ac clutch engages and blows cold air.
So I know I have power at the plug, and I know the compressor works, and I know there is continuity from the plug to the compressor, so I thought the sensor must be the issue.
The problem is that I tried jumping one lead of the plug to the other, and it doesn't work, so maybe the sensor is fine? I am totally confused how one end is getting power, and the compressor works fine when I power the other end, but it doesn't work when jumping it. The only thing I can think of is that the battery has 13 volts and the plug has 11 volts, but is that a big enough drop where the compressor clutch won't engage?
Maybe there is something obvious I am missing in my test?
Thanks. If no replies I'll just post a new thread.
So I know I have power at the plug, and I know the compressor works, and I know there is continuity from the plug to the compressor, so I thought the sensor must be the issue.
The problem is that I tried jumping one lead of the plug to the other, and it doesn't work, so maybe the sensor is fine? I am totally confused how one end is getting power, and the compressor works fine when I power the other end, but it doesn't work when jumping it. The only thing I can think of is that the battery has 13 volts and the plug has 11 volts, but is that a big enough drop where the compressor clutch won't engage?
Maybe there is something obvious I am missing in my test?
Thanks. If no replies I'll just post a new thread.
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