A/C makes metallic ticking sound

[EDCivic]

I recently had our ED Civic's a/c retro fitted to R134a and must admit works quite well, except when the the revs drop below 1,000 rpm where it then makes a metallic ticking sound. It never did it before the retro fit but because it started blowing hot air last summer I had no choice but to have it converted when it was "fixed". I went back to the a/c mechanic and he reckons that when the gas was evacuated and replaced some gunge must have caused one of the vanes in the compressor to become sticky at low revs. He could only suggest that he tries a new additive that has just come onto the market that makes the a/c more efficient. Any ideas

[fusionprelude]

did they fill the gas to the correct amount did they change the the reciever dryer.. if all this i suggest possibly changing the ac compressor and regasing it

[bennjamin]

the metal sound , sounds like the engine struggling/overloading and "pinging".

Try a higher rated fuel such as 95 or 98 octane or alter your driving style to put less load on the engine

[EDCivic]

the metal sound , sounds like the engine struggling/overloading and "pinging".

Try a higher rated fuel such as 95 or 98 octane or alter your driving style to put less load on the engine

No, unfortunately the engine is not pinging. And they did change the dryer etc. It just p*sses me off that it worked fine for the 10 or so years we had the car and just as last summer finished the a/c gave out. Get it retro fitted and it now makes this noise. There is an oil additive called "envirotemp" that is sold here in SA which supposedly increases the efficiency of the a/c system by interacting with the oil in the a/c system. don't know might give it a go else keep running it till it destroys itself ?????

[ECU-MAN]

the sound is die to the A/C system being over gassed or Over pressured.