My A/C system has new compressor, but It still doesn't blow cold air in idle or local driving. It only works on highway. What would be the problem? Expasion Valve?

I'm no guru, but #1 is your aux fan working in idle? Does the water temp go above 100 while in idle with the A/C on? When is the last time you had the pressure / level of freon checked? What is the actions of the water temp gauge while in idle / driving? Does the A/C act any differently while the fan is in LO/Med or HI?



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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

Did you by any chance get it filled with 134 refrigerant instead of R12? If so, that is a common problem with these type conversions. Works great at highway speeds but doesn't cool very well in city driving or stop and go traffic. Maybe a vacuum and fill with R12 is the answer.

Ockman made a good point about R134 and it's limited capacity, however, if you have already changed to R134 and you want to change back, proceed with caution. You don't want R134 to mix with R12 in any way, don't even get them close to each other. If you decide to switch back, which I wouldn't do at all, make sure you get the compressor completely clear of the old oil. Then completely disconnect everything in the a/c system and flush "thoroughly".

I don't think that the aux. fan not working would have a drastic effect on cooling ability, the main reason for its existence is to bring down high side pressure when it gets too high. This keeps from blowing something out.

If your system is still R12, I expect that it is inadequately charged, but don't assume so and add R12 without checking everything first.

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Thank you All. The aux. fan's working fine.
It turned out to be Failed Recirc servo.
so it was chilling 110 degree outside air.
Now I found the remedy and it's working fine.

quote:

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Originally posted by LarryBible:
Ockman made a good point about R134 and it's limited capacity, however, if you have already changed to R134 and you want to change back, proceed with caution. You don't want R134 to mix with R12 in any way, don't even get them close to each other. If you decide to switch back, which I wouldn't do at all, make sure you get the compressor completely clear of the old oil. Then completely disconnect everything in the a/c system and flush "thoroughly".

I don't think that the aux. fan not working would have a drastic effect on cooling ability, the main reason for its existence is to bring down high side pressure when it gets too high. This keeps from blowing something out.

If your system is still R12, I expect that it is inadequately charged, but don't assume so and add R12 without checking everything first.

Good luck,

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