A/C question

[sonyhome]

The A/C of a 2002 forester doesn't work. What could be the problem?

 

Turning the A/C on doesn't make the AC metal lines cold in the engine. How do I know it engaged or not, if not why, and if yes why it's still warm?

 

- Can the compressor or any expensive part be damaged from not being used (aka I'm thinking no lubing) knowing the car's 4/5 years old?

 

- Is it just low on coolant? If so why would it leak, and what's the ballpark cost of an AC purge + refill?

 

- Fuses? There must be fuses for the AC. Where is the fusebox? Is there more than one? Are the fuses labelled with their purpose (I have limited access to the car simple knowledge can help me move fast to work things out).

 

- Anything else that could cause the failure, or symptoms or things to look for to push the diagnostic and home in on the problem?

 

Thanks!

[OB99W]

The A/C of a 2002 forester doesn't work. What could be the problem?

There are several possibilities, including a simple one. To help with understanding automotive A/C and responses to your questions, see:

http://endwrench.com/images/pdfs/ACTheory.pdf

http://endwrench.com/images/pdfs/ACMechanism.pdf

 

 

Turning the A/C on doesn't make the AC metal lines cold in the engine. How do I know it engaged or not, if not why, and if yes why it's still warm?

Turning the A/C on should cause the magnetic clutch at the front of the compressor to engage. The simple possibility: A very low refrigerant (not "coolant"; that's the stuff in the radiator) level will cause a pressure switch in the receiver/drier to open and not allow the clutch to engage. (A somewhat low refrigerant level may be sufficient to allow the compressor to operate, but provide poor cooling.)

 

 

- Can the compressor or any expensive part be damaged from not being used (aka I'm thinking no lubing) knowing the car's 4/5 years old?

Automotive A/C systems are internally lubricated; there is refrigerant oil in the system. However, the A/C should be periodically turned on to distribute that oil. In particular, the shaft seal for the compressor is more prone to leaking if not lubricated, leading to a more-likely loss of refrigerant.

 

 

- Is it just low on coolant? If so why would it leak, and what's the ballpark cost of an AC purge + refill?

Besides the compressor shaft seal, there are tubing fittings that can become leaky due to having loosened from vibration or seals having failed. Repair costs will vary depending on how much refrigerant is needed, leak detection diagnosis, possible seal replacement, etc.

 

 

- Fuses? There must be fuses for the AC. Where is the fusebox? Is there more than one? Are the fuses labelled with their purpose (I have limited access to the car simple knowledge can help me move fast to work things out).

That information should be in your owner's manual.

 

 

- Anything else that could cause the failure, or symptoms or things to look for to push the diagnostic and home in on the problem?

The above should get you started. Feel free to ask more questions.