QuestionQUESTION: after the a/c compressor in my 2005 Toyota Avalon was replaced the climate control panel stopped working completely. The mechanic says that he cannot access the system with his scan tool even though it is CAN compliant. He is able to access all other systems on the car. Fuses are apparently fine. Any thoughts what might be wrong?
ANSWER: Hello,
Can you be more specific about your symptom? Does it not light up? Fan doesn't work? not heat or ac controls?
Wayne
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QUESTION: Nothing on the panel works. No lights even. No heat, a/c, defrost etc.
ANSWER: An avalon panel is called the 'Digital amplifier'. There are more than one fuse that powers this system up and they must be checked very thoroughly. Once they are checked and good pull the panel out and check for the power and grounds at the back of the amplifier. Battery voltage is at pin 1 and ignition voltage is at pin 21, ground for the circuit is on pin 20.
If you have battery voltage at these two pins and ground on pin 20 and nothing lights up the amplifier is defective. They are expensive so get a used one. They do not have to be programmed.
By the way this compressor has a sensor in it called a lock sensor. It tells the amplifier when to disengage clutch if the clutch is slipping. They relay in this circuit is notoriously common for failure.
To my recollection there is no datastream from teh climate control head. I have never had to access one with my computer.
Wayne
---------- FOLLOW-UP ----------
QUESTION: the mechanic said he has no voltage at pin 21. he applied power there and it still doesn't light up or work.
Any idea why there is no power to pin 21 and as a follow-up why would it not work when external power is applied.
Did replacing the a/c compressor somehow cause these problems. Thank you very much for your advice.
AnswerIt will need power at PIN 1 AND PIN 21. One is battery and one is ignition voltage (key on and key off)
If you have power on both of these circuits and ground on pin 20 (did he check that?) the panel is defective.
I suspect something shorted out. Check the HTR fuse and the A/C fuses if they are not powered up there is a problem with a fusible link or panel issue.
Wayne
******** To answer your question there shouldn't be any reason that the panel was destroyed by installing a compressor if the battery was disconnected. If you don't disconnect the battery while servicing vehicles however anything can happen. Seems very suspicious. I have never had to replace a Toyota climate control panel. I have done a few compressors, lots of condensers and rear air related stuff on the vans etc but never an HVAC panel. They are very well built cars.
Wayne
