1994 C280 AC Suction hose stumper (or question) - PeachParts Mercedes-Benz Forum

crashone · #1 08-09-2008, 01:10 PM

Hope someone can shed some light. I have my C280 at the shop getting the AC system fixed, ie: new compressor, dryer, exapansion valve and charge.

Here is the problem: All pressures are perfect, compressor kicks on, the suction hose will not get cold. Tried another compressor to check if it was bad, still same condition.

If there was a restriction in the system then the pressure would not show correct readings so that is not it.

Can this be related to a bad douvalve or what? What else to check?

Thanks for the help.

Matt L · #2 08-09-2008, 01:18 PM

Was the system charged by weight or pressure? If the latter, you could have a restriction with the proper pressures.

You can isolate the duovalve by carefully clamping the water hose going to the engine.

crashone · #3 08-09-2008, 05:52 PM

Thanks, I'll check on weight vs pressure.

duxthe1 · #4 08-09-2008, 10:07 PM

DUO valve will not keep the suction hose from getting cold. It sounds like a restriction to me. I'd feel over all the a/c hoses to see if you can find a spot where the hose is cold, that would likely be the restriction assuming it isn't somewhere buried like the evaporator.

crashone · #5 08-10-2008, 09:22 PM

If there was a restriction wouldn't the pressure be wrong? Thanks.

duxthe1 · #6 08-10-2008, 10:39 PM

It depends on where the restriction is. There is already one metered restriction and sometimes another restriction can mimic it. Problem restrictions usually occur at the receiver drier, exp. valve or evaporator.