1984 300SD: A/C Vent temperature question - Page 3 - PeachParts Mercedes-Benz Forum

funola · #31 08-07-2013, 05:56 PM

Quote:

Originally Posted by jcyuhn

No, definitely not. But if you have 55PSI low side at idle, you're not going to get decent cooling from either refrigerant.

OK.

I was just saying that (in my previous post) my 85 300D, with an R4 converted to R134 (by previous owner but done professionally), topped up by me (with not much AC experience) since it was not cooling very well, achieved better cooling at idle than his system with R12, so something must not be right in his system.

seebeexee · #32 08-12-2013, 01:23 PM

Quote:

Originally Posted by ROLLGUY

Has anyone thought about a bad (or marginal) mono valve letting some heat in as well?

I just checked the hoses that are attached to the mono valve after a 45 minute drive, and they're cold, so it appears that my mono valve is OK and that I'm not getting any hot coolant coming in creating heat. That's good...

Quote:

Originally Posted by funola

Don't know how the SD is layed out but on my 85 300D, I removed the panel under the glove box, removed 3 screws or bolts and the blower drops down, unplug connector and the blower is out of the way to spray evap cleaner and water (huge amounts) in there. I removed the drivers side center console panel (by your right knee) to get access to the foam tube. The soda bottle funnel is to direct water flow so it all goes out of the car instead of splashing all over inside.

Thanks for the description. I'm going to try that when I get some time to tear things apart.

Whiskeydan · #33 08-12-2013, 03:08 PM

A 28 tube and fin condenser isn't going to provide very good performance.

To prove this, try misting the condenser with water and note the cabin vent temp and suction, discharge pressures.

seebeexee · #34 08-14-2013, 11:20 PM

Quote:

Originally Posted by Whiskeydan

A 28 tube and fin condenser isn't going to provide very good performance.

To prove this, try misting the condenser with water and note the cabin vent temp and suction, discharge pressures.

Agreed. I actually tried that on the day I charged the system when I realized the vent temps weren't cold enough. Misting the condenser dropped the vent temperatures a noticeable amount just by feel, let alone on the thermometer.

What type of condenser is recommended for an R12 system with the R4 compressor?

Now, I'm very frustrated with the A/C system. It's still fully charged, and with ambient temperatures in the mid 70s (morning), vent temperatures reach 40*F. However, when ambient temperatures reach 95*F, the A/C feels like a heater and provides virtually NO cooling, with vent temps literally equal to ambient temperatures. If I put the fan speed on low, there is about a 5* difference, but that's it.

The system is still fully charged, the compressor is turning, and the condenser fan works properly, but in hot weather, the A/C is providing virtually no cooling. I haven't gotten around to cleaning the evaporator yet, but I don't see how that would cause the sudden lack of efficacy in the system.

Anyone have any additional ideas?

Whiskeydan · #35 08-15-2013, 12:01 AM

W126 AC woes solved