Having a couple of problems with the A/C on my '82.

1) Blows 'cool', not cold. Cold is a requirement here in Phoenix, it's 100+ here now. I'm taking it to shop tomorrow to check freon level. I did have the A/C belt break last week, replaced this weekend. Compressor pulley spun freely, so I went ahead with replacing the belt. I'm guessing it was old, as my PS belt was cracked as well.

2) Center vents on dash- I don't get any 'cool' air from these vents, nor from the vent to the rear seat from the center console. They only blow ambient air, which is now like a heater!

And finally, I noticed over the winter that my heat was intermittent. I'm guessing it's the monovalve, but I didn't think the monovalve was related to A/C, is it?

Thanks,

Adam

The monovalve absolutely is related to the a/c. The way it works is that the a/c is cooling the evap basically all the time. The temp out the vents is regulated by adding hot air via the monovalve. If the monovalve is leaking the a/c system itself could be working great but the air will be hotter than you know what.

Take out the four screws at the top of the monovalve and see if it is flooded below the top plate. If so, click on fastlane above and get a rebuild kit.

Good luck,

Thanks Larry, I'll check it out tonight. Might save me a trip...

OK, the monovalve diaphram is torn, so new one on order from Phil today, along with other goodies since you can't order just one thing...

That rear vent in the console does not get any AC conditioned air. it will only blow ambient air no matter the setting on the temp wheel.

The center vents on the other hand get their AC cooled air via the "scoop air flap" which is controlled by vacuum valve number 4, color green on the passenger side of console. The pod is located on the drivers side foot well behind the carpet.

If the diaphragm for this pod is torn and it does not open then you will only get ambient or heated air, especially if the monovalve is bad. It could also be the vacuum valve is bad to the scoop flap so it is not opening the pod when it needs to.

I've gotten pretty good at testing these with a mity vac and a digital multimeter.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

I disagree. The rear vent ABSOLUTELY gets A/C air on a 82300SD. It is not supposed to get heated air, but if the monovalve is leaking it will.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

I can't wait for a sunny day to test my cars. I have never noticed the cold air and according to the owners manual on the 81 it says that it only receives ambient air.
I'll try them all and let you know.
Thanks

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Perhaps this is one of the differences between years. My 82 Owners Manual says the rear outlet is supplied "either non-heated, fresh air or cooled air". When my A/C worked, it put out a good amount of chilled air. Quite a number of changes were made between 81 and 82.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.