AC Compressor not running
- Thread starter bcossa2001
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What model avalon is this?
1997 XL
Do the electric cooling fans come on automatically when the engine heats up, do the come on with the A/C switch?
Too late to edit. It looks like Temp sensor 1 is connected to the A/C pressure switch. That may well be the problem. Its probably a green 2 blade connector (not 100% sure).
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Both fans come on with the AC. I believe only 1 comes on when the coolant temp gets too hot..
Wouldn't jumping out the pressure switch bypass this?.
No it wouldn't, its pre pressure switch, you are jumping a dead switch.
Any idea how I can test the pressure switch to see if it is dead?
With pressure in the system the switch should be closed. If you are jumping the connector and its not kicking on its not the switch.
Check for voltage going to the switch coming from temp sensor #1. I suspect there is no voltage going through the coolant switch to the low pressure switch.
Check for voltage going to the switch coming from temp sensor #1. I suspect there is no voltage going through the coolant switch to the low pressure switch.
Well we're having fun anyway
Can't tell which coolant temp switch is #1 and which is #2 as they are both mounted on the stat housing. One switch reads open blow 190 and closed above 190. The other switch reads closed below 190 and open above 190. One is a 2 pin and one is a one pin. Both fans kick on at 198 and kickoff at 194. The pressure switch reads open at 194 degrees and closes about 185 degrees.
I'll assume what the Haynes manual tells me is correct as far as switch switch is #1 and check voltage tomorrow as Trav suggests.
Thanks very much to everyone for their advice and interest...
Can't tell which coolant temp switch is #1 and which is #2 as they are both mounted on the stat housing. One switch reads open blow 190 and closed above 190. The other switch reads closed below 190 and open above 190. One is a 2 pin and one is a one pin. Both fans kick on at 198 and kickoff at 194. The pressure switch reads open at 194 degrees and closes about 185 degrees.
I'll assume what the Haynes manual tells me is correct as far as switch switch is #1 and check voltage tomorrow as Trav suggests.
Thanks very much to everyone for their advice and interest...
Sensor 1 has 2 wires and sensor 2 has 1 wire, just jump the connector on the 2 wire plug with the A/C turned on, if it kicks on you found the problem.
Disconnected the 2 wire plug and both the fans came on. Jumped out the plug and the fans turned off. No luck on the compressor...
Also confirmed voltage to the pressure switch. It has 4 terminals and there is voltage to 2 of them..
Also confirmed voltage to the pressure switch. It has 4 terminals and there is voltage to 2 of them..
Did you check the A/C fuses? You say you jumped the pressure switch and got nothing?
Yes and yes...
You need to get the full schematic and trace through the whole circuit. It appears that one of the temperature switches is designed to open if the engine starts to overheat, which shuts down the compressor. So this switch should be closed circuit normally (not overheated). It is in series with the pressure switch. Both must be closed for the compressor to come on.
The 4-wire pressure switch probably has one circuit for the compressor and another for the fans. This means that if you unplug the switch to jump it, the fans will not respond to refrigerant pressure. Running the compressor with no fans will cause an overpressure which-- without the pressure switch operational-- will blow a hose or pop the relief valve. So if you go jumping things and the compressor does start, do it for only a very short time (a second or two) so that pressure does not build up.
The 4-wire pressure switch probably has one circuit for the compressor and another for the fans. This means that if you unplug the switch to jump it, the fans will not respond to refrigerant pressure. Running the compressor with no fans will cause an overpressure which-- without the pressure switch operational-- will blow a hose or pop the relief valve. So if you go jumping things and the compressor does start, do it for only a very short time (a second or two) so that pressure does not build up.
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+1 time to start at the beginning. A/C power on is there power to the clutch and go from there. The trick is to find out at what point there is power and determine if the switch or relay is being triggered to let the power go where its supposed to next. This sort of carry on make for a long day or just a few min.
I try to at least determine if the issue is inside the car or under the hood and work from there.
I try to at least determine if the issue is inside the car or under the hood and work from there.
Where does one get the proper wiring diagram for their specific vehicle? All the Haynes manual contains is a generic one..
I usually get DVD or a book on ebay if its something I don't have. This is for a 96 but its probably the same, they didn't change much of anything electrical 94-99.
For $25 its cheaper than an online resource. There are others I just picked this one.
http://www.ebay.com/itm/1996-TOYOTA-AVALON-Electrical-Wiring-Diagrams-Service-Manual-EWD-Troubleshooting-/311823744820?hash=item489a24bf34:g:XMQAAOSwXYtYyIfV&vxp=mtr
edit: There are pdf files like this you can print out.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwiLyKyYzeLSAhVF7SYKHR8uBHcQFgg3MAk&url=http%3A%2F%2Fautolib.diakom.ru%2FCAR%2FToyota%2F1997%2FAvalon%2FSYSTEM%2520WIRING%2520DIAGRAMS%2F12040.pdf&usg=AFQjCNGxFgvaGaeTUK0gwdh8QH_VrtlyMw
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=0ahUKEwiLyKyYzeLSAhVF7SYKHR8uBHcQFghOMA0&url=http%3A%2F%2Fwww.autocats.ws%2Fmanual%2Ftoyota%2Fcamry20%2Fcontent%2F97_NCF.pdf&usg=AFQjCNH9IlC1BkpUsY3DB9SLOgZYQj6kpQ
For $25 its cheaper than an online resource. There are others I just picked this one.
http://www.ebay.com/itm/1996-TOYOTA-AVALON-Electrical-Wiring-Diagrams-Service-Manual-EWD-Troubleshooting-/311823744820?hash=item489a24bf34:g:XMQAAOSwXYtYyIfV&vxp=mtr
edit: There are pdf files like this you can print out.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwiLyKyYzeLSAhVF7SYKHR8uBHcQFgg3MAk&url=http%3A%2F%2Fautolib.diakom.ru%2FCAR%2FToyota%2F1997%2FAvalon%2FSYSTEM%2520WIRING%2520DIAGRAMS%2F12040.pdf&usg=AFQjCNGxFgvaGaeTUK0gwdh8QH_VrtlyMw
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=0ahUKEwiLyKyYzeLSAhVF7SYKHR8uBHcQFghOMA0&url=http%3A%2F%2Fwww.autocats.ws%2Fmanual%2Ftoyota%2Fcamry20%2Fcontent%2F97_NCF.pdf&usg=AFQjCNH9IlC1BkpUsY3DB9SLOgZYQj6kpQ
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