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Eric
Eric, Automotive Repair Shop Manager
Category: Toyota
Satisfied Customers: 24692
Experience:  20+ yrs. experience as repair shop manager and technician.
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Toyota Corolla CE: A/c compressor not running. Whyever not

Resolved Question:

A/c compressor not running. Whyever not?
Submitted: 1 year ago.
Category: Toyota
Expert:  Eric replied 1 year ago.
Hi,

what year corolla is yours?
Customer: replied 1 year ago.

2004 - didn't that show up? I selected it.

Expert:  Eric replied 1 year ago.

Hi,

for some reason it didnt show it on my side.

Ok, the pressure switch is on the right side of the engine compartment

graphic


 

 

Expert:  Eric replied 1 year ago.
graphic


graphic
Customer: replied 1 year ago.

Eric, OK, found the switch. Is there any other reason for the compressor clutch not to get power? The refrigerant pressures are OK and the in-cabin 10A fuse is good. (The switch is over $200., and the dealer doesn't have it in stock.)

Expert:  Eric replied 1 year ago.
HI,

yes, there are other reasons. no signal from climate control panel, no signal from the ecm to the compressor clutch relay. But the most common is the switch.

Below is testing for the switch. If it test good, let me know and we will go from there:
graphic

Customer: replied 1 year ago.

This is interesting - there is continuity between terminals 1 and 4 in the range indicated, but the pressure doesn't get to the range, below 28psi/above 455psi, that should open the switch. Plugging the connecter in makes the fan operate, but not the clutch. Maybe an open circuit between the switch and the clutch? Should I make a jumper connection between the switch and the wire to the clutch near the clutch? But wait, late breaking discovery - no power to either 1 or 4 at the switch. Which one should be powered, and from where?

Expert:  Eric replied 1 year ago.

Hi,

Ok, terminal #1 goes to the ECM and sends signal to it

Terminal #4 is ground and is opened and closed by climate control panel.

it sounds like either no signal between the switch and the ecm, or none from ecm to clutch relay.

Customer: replied 1 year ago.

This is a cycling compressor, not a variable displacement one, is it? (Thinking of borrowing power from the fan control part of the switch - that might indicate whether the grounding function is working - if it didn't blow up while testing.


The control panel A/C light comes on on demand, if that tells us anything.


 


Where do I go from here?

Expert:  Eric replied 1 year ago.
Hi,

yes, it is a cycling compressor

have you tried a jumper wire between terminal 1 and 4 on the switch connector? try this to rule out the switch. If the compressor runs, then replace the switch.

If no go, then run a jumper from pin #1 to connector A pin #13 on the ecm and see if it runs.

If no go, then check for power out at connector C pin #2(yellow/black wire) on the ecm.

If power, then check for 12v on pin #2 on ac clutch relay. If no power, then repair short in the yellow/black wire from ecm to relay or just replace that wire.

Customer: replied 1 year ago.

Excellent. "I'm on it!"

Expert:  Eric replied 1 year ago.
Hi,

ok, let me know how it goes
Customer: replied 1 year ago.

Eric, jumping 1 and 4 makes the compressor cycle, but it pumps for just a couple seconds and kicks out, so doesn't make cold air. Switch, for sure? (Rock Auto lists them for under $20.)
Stephen

Expert:  Eric replied 1 year ago.
Hi,

Yes, definitely the switch. with the connector jumpered, there is signal to the ecm and from ecm to relay and relay to the compressor. Replace the switch and it will be good to go
Eric, Automotive Repair Shop Manager
Category: Toyota
Satisfied Customers: 24692
Experience: 20+ yrs. experience as repair shop manager and technician.
Eric and 7 other Toyota Specialists are ready to help you
Customer: replied 1 year ago.

You were right - again. Cold air all over the place. Too bad Toyota couldn't have afforded a little valve to enable the switch to be changed without evacuating/recharging. But ohhh, no. They saved a quarter of a cent per vehicle. Legendary something.

Expert:  Eric replied 1 year ago.
Hi,

always glad to help.

i agree, and most due have the switch screwed onto a port with a shrader valve inside it to prevent having to evacuate the system.
Eric, Automotive Repair Shop Manager
Category: Toyota
Satisfied Customers: 24692
Experience: 20+ yrs. experience as repair shop manager and technician.
Eric and 7 other Toyota Specialists are ready to help you

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