1987 300SDL purchase--Warning, A/C drama!
 

My esteemed colleagues,

I bought an '87 SDL with 200k on the clock. It still has the trap ox, and I'm wrangling with the local dealer over the recall (are all dealers in denial about it?) Unfortunately, I'm in Florida, and the A/C isn't blowing cold, just tepid.

Here's what I know:

1. The compressor engages;
2. The refrigerant (R12) is fully charged;
3. The refrigerant circulates ("gurgles" behind the dash) when the A/C is activated.

All fingers--and research--point to the monovalve, which I plan to repair with a kit tomorrow. Still, I have a sneaking suspicion this is no quick fix. Does anyone else know of a situation similar to this one? I'm especially intrigued at how all the cooling components operate, yet fail to cool. If I don't get this fixed, I'm one stuck (and hot) pig.

Thanks!

Damon

you shouldn't have to wrangle with them to do the trap oxidizer. They get reimbursed for the work by MBUSA. Go elsewhere. And keep that R12!

I take it that you haven't put pressure gauges on the system. You could be getting the wrong flow though the expansion valve, either too little or too much. I'm guessing too much.

Condensor could be dirty too, poor fan clutch also. Non functional Aux Fan.

When Monovalves fail, you usually don't have heat...

More information about my A/C woes...
 

All,

Thanks for your feedback thus far. I installed a new monovalve kit and have "quicker" heat, but still no cool air. The auxiliary fan is blowing away, and I have no idea whether or not the condensor is dirty. As for the bottle with the refrigerant looking glass, it shows the movement of gasses inside (ever so slight), but there is no cooling of the pipes leading from it. Would a dirty condenser prevent such cooling?

Also, does anyone know the proper low-side pressure for this R12 system? I suspect the refrigerant may be low, but don't want to speculate. ALLDATA and all the archives I've searched reveal nothing of substance.

Many thanks!

DL

What about the fan clutch?

It's possible the compressor is old and not pumping out enough pressure. There's a chart somewhere online regarding high versus low side pressure dealing with ambient temps.

Condenser after twenty years gets full of debris, bug guts, etc.

Might be a bad expansion valve. Have you had it checked by someone who knows AC systems?

Sixto