Was sitting in the car running it at 1500 rpm and feeling the temp of the ac coming out of the vent . Then there was a sound from under the hood like loud hissing and a small cloud of white smoke came out from under the drivers side of the hood. I later inspected it carefully at night with a flashlight and mirror but could not see any holes. There was some green oil on the power steering hoses near the compressor. I put the gauges on and there was 90 psi in the system, I didn't start the car and check any further. My guess now is that while sitting still in the driveway and running the car at 1500 rpm, without the cooling fan coming on the high side pressure rose and blew out the extra pressure around one of the O rings maybe at the compressor.
More checking required, I'll try to find another brown sensor and see if that makes a difference.
AC system rebuilt but compressor squeaks loud-93 940
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rollin_home
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jimmy57
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There is a valve, screwed onto the high side line on RH side as I remember, that dumps pressure at 425 psi give or take a few psi. If the fans didn't come on then it got too high and relieved pressure.
you need both fan switches if the fan never came on. The low speed sw shopuld have triggered fan and when it didn't and pressure got higher the hi fan sw should have turned fan on high speed.
If you jumper the grey switch does fan run on high?
If you are going for used switches then find ones that have a rubber band around switch just above where metal is rolled over the colored plastic connector part. Early switches do not have this and have high failure rate with age. Later ones have a hole and the black rubber band covers that hole. If diaphragm leaks a bit it won't stay captured in the end of switch and raise the cut on pressure of switch.
you need both fan switches if the fan never came on. The low speed sw shopuld have triggered fan and when it didn't and pressure got higher the hi fan sw should have turned fan on high speed.
If you jumper the grey switch does fan run on high?
If you are going for used switches then find ones that have a rubber band around switch just above where metal is rolled over the colored plastic connector part. Early switches do not have this and have high failure rate with age. Later ones have a hole and the black rubber band covers that hole. If diaphragm leaks a bit it won't stay captured in the end of switch and raise the cut on pressure of switch.
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rollin_home
- Posts: 88
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- Location: AWD
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Hi ,
I drove the Volvo 940 this evening and I was very happy to see that the ac is still working, while moving. I didn't bother to try it again not moving. Looking at it again but this time with Jimmy's suggestion of an over pressure valve, I think that there is one. On the back of the Sanden compressor below the small port there is this hex shaped post about 1" long and with a hole in the center of the end. Opposite this are the power steering lines and that is also where they have a fresh coating of greenish ac oil. So, that must be the explanation, thanks Jimmy. The fact that the system still works means that its pretty tight and things like my non-oem HF green O rings held, as did the tig welds done to my used ac lines, all good news. My guess is that I didn't lose too much refrigerant the ac is still cold, maybe it could take a bit more but its hard to know as it is definitely blowing cold air.
Now to the sensor, both the grey and the brown connectors , when jumper ed , turn on the fan. But as far as I can tell there isn't any difference in the fan speed when brown connector is jumper-ed vs gray. The fan runs plenty fast for both, a good whoosh and strong draft of air. It seems like it would cool a hot condenser while the car is idle. Its hard to believe but both switches may be bad, I wish there was an easy way to test them . I'll look on craigslist for somebody who is parting out a 940 . If that doesn't pan out, then I'll get new ones .
I should mention that the system was 'open' for a couple of years before this last rebuild, maybe that caused the pressure switches to go bad.
Anyway , thanks for your feedback, much appreciated.
Tim
I drove the Volvo 940 this evening and I was very happy to see that the ac is still working, while moving. I didn't bother to try it again not moving. Looking at it again but this time with Jimmy's suggestion of an over pressure valve, I think that there is one. On the back of the Sanden compressor below the small port there is this hex shaped post about 1" long and with a hole in the center of the end. Opposite this are the power steering lines and that is also where they have a fresh coating of greenish ac oil. So, that must be the explanation, thanks Jimmy. The fact that the system still works means that its pretty tight and things like my non-oem HF green O rings held, as did the tig welds done to my used ac lines, all good news. My guess is that I didn't lose too much refrigerant the ac is still cold, maybe it could take a bit more but its hard to know as it is definitely blowing cold air.
Now to the sensor, both the grey and the brown connectors , when jumper ed , turn on the fan. But as far as I can tell there isn't any difference in the fan speed when brown connector is jumper-ed vs gray. The fan runs plenty fast for both, a good whoosh and strong draft of air. It seems like it would cool a hot condenser while the car is idle. Its hard to believe but both switches may be bad, I wish there was an easy way to test them . I'll look on craigslist for somebody who is parting out a 940 . If that doesn't pan out, then I'll get new ones .
I should mention that the system was 'open' for a couple of years before this last rebuild, maybe that caused the pressure switches to go bad.
Anyway , thanks for your feedback, much appreciated.
Tim
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rollin_home
- Posts: 88
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- Year and Model: 99 s70, 08 s60, xc70
- Location: AWD
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Hey Jimmy,
I bought 3 used switches from a fella on Craigslist for $15 delivered, cheap enough to take a chance. Tonight, I put the brown switch on a tank of nitrogen and ran the pressure up to 310psi with a continuity tester on the switch leads. Despite repeatedly running up the pressure to 300+psi the switch never closed so I guess its a dead switch. I'll test the others against the specs you gave me:
"....brown switch closes at approx 230 and reopens at approx 165. grey switch closes approx 310."
Tim
I bought 3 used switches from a fella on Craigslist for $15 delivered, cheap enough to take a chance. Tonight, I put the brown switch on a tank of nitrogen and ran the pressure up to 310psi with a continuity tester on the switch leads. Despite repeatedly running up the pressure to 300+psi the switch never closed so I guess its a dead switch. I'll test the others against the specs you gave me:
"....brown switch closes at approx 230 and reopens at approx 165. grey switch closes approx 310."
Tim
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