240D A/C Not Blowing Very Cold - PeachParts Mercedes-Benz Forum

dantheman67 · #1 06-23-2010, 07:15 PM

Hi,

I know I'm adding to the piles of A/C related threads, but I've got a dilemma.

My Freeze 12 setup is not cooling sufficiently. On a 90F day, it blows (an estimated) 55 to 60 F at the vent. What's wrong? I gotta get this A/C working. Help!

Important info:
-Compressor is turning.
-System was empty when I got the car
-Running Freeze 12 (system took about 1.2 cans)
-I added about 4 to 6 oz of POE Oil
-With Compressor running, High side pressure is ~165 psi; low side pressure is ~35 psi
-The line right out of the R/D leading to the Expansion Valve is very hot when the compressor is turning.
-The Expansion Valve is chill but not COLD; feels about the same temp as the air coming out of the vents
-My car has the manual climate control; not sure if there is a monovalve in my setup.

leathermang · #2 06-23-2010, 09:03 PM

Show us a picture of the dash and the engine compartment... especially the top of the firewall just to make sure...with respect to the type AC system you have..

You did not mention pulling a vacuum on the system ... if you did pull one give us the specs.. why was the AC not working when you started working on the AC system ?
Has it been working and is just now NOT cooling... ?
Did you flush the system before putting in refrigerant ?

dantheman67 · #3 06-23-2010, 10:01 PM

I decided to tackle the A/C system recently. It's never been operational during my ownership of the car....

The pressure switch screw-in fitting to the R/D was not in tightly and was leaking. I tightened it so it doesn't leak anymore. Haven't run vacuum test, but listened and don't hear any more leaks. I didn't flush the system since I turned the compressor and it seemed good.

Btw I left the temp switch disconnected because the aux fan bearings are shot and sound terrible when the fan's on.

Edit: Added pic of manually operated heater valve. Next to the battery.

Pictures in 4...3...2...1....

leathermang · #4 06-23-2010, 10:19 PM

To be honest with you ... you started working on it before doing enough research..
there are a lot of great threads on fixing AC on this forum... which can be found with the search feature..you need to learn about the basics of AC and then how your system works and its needs..... inside the AC is a very harsh and physically demanding place... and has to use all the physics properly to do a good and long lasting job of keeping you cool...
Also, there are sites like Aircondition.com and ACKits,com which have lots of good info....

quackattak · #5 06-24-2010, 09:52 AM

I just replaced a hose and mine is working for the first time, your car had no freon when you started working on it so at least you need to evac the system to remove any air. Also if you have to much oil, which I think you might now. You need to replace your drier, only $35-40. I used R134 just because thats what I use at work and its easy to get a hold of. I have heard enough negative things about freeze12 that I have never tried it. After saying all this, I do agree with the others that R12 is the best thing to put in these older systems.

rrgrassi · #6 06-24-2010, 10:30 AM

How long have you owned the car?

If there was no freon, you should have at least replaced the drier and pulled a vacuum. The vacuum does remove air as previously noted, butthe primary function of the vaccum is to remove moisture.

bobodaclown · #7 06-24-2010, 12:38 PM

I think 30 degrees temp drop is pretty routine. There are factors such a humidity and such.
Some more reading: http://www.schnitzer.net/dana/ac_temp_basics.html

dantheman67 · #8 06-24-2010, 07:46 PM

Thanks all. Leathermang, I scoured the existing threads prior to creating this one and have been studying A/C operation. I'm no pro, but this is where I'm at.

I ordered a new Behr R/D, Uro expansion valve and o-rings today and should get them in a week.

I plan to flush the condenser and evap, and draw vacuum prior to recharging the system (with R12).

Will keep you all updated....

engatwork · #9 06-24-2010, 07:59 PM

Another year and time for hot weather related a/c topics.

The best thing I ever did to resolve my weak a/c issue was to move up to the 95 E300

. The wife and I both have one but I hardly ever drive anymore. You can make the W123 blow cold when using r12. I have yet to see one work well around here running r134 but it gets hot here.

leathermang · #10 06-24-2010, 08:14 PM

Quote:

Originally Posted by dantheman67

Thanks all. Leathermang, I scoured the existing threads prior to creating this one and have been studying A/C operation. I'm no pro, but this is where I'm at.

I ordered a new Behr R/D, Uro expansion valve and o-rings today and should get them in a week.

I plan to flush the condenser and evap, and draw vacuum prior to recharging the system (with R12).

Will keep you all updated....

Ok, now you are on the right track...
I wrote what I did because of this statement

" Haven't run vacuum test, but listened and don't hear any more leaks. I didn't flush the system since I turned the compressor and it seemed good."..

Listening is not good enough to detect leaks...and not flushing on a system of unknown condition or history is the way to turn a good compressor into junk... way cheaper to flush and do things right the first time...

For flushing the evaporator the AC MB FSM suggests you keep the old TxValve and turn it into a tool .... The AC MB FSM is a great read... very specific compared to some of the FSM's like the chassis manuals.... it tells which direction to flush the hoses, that if a compressor 'meltdown' has occurred to replace the metal manifold instead of trying to flush and clean it... this is something seldom mentioned on the forum but clearly stated in the MB AC FSM.... and lots of other warnings are that way too...
Also, always wear goggles when doing AC work...

dantheman67 · #11 08-14-2010, 12:47 AM

Good News,

I got my parts in last week. The supplier I bought the TxValve from said the device needed TWO o-rings (they provided part #s), so I bought those TWO o-rings. After a lot of frustration about why my R12 was leaking out of my brand new valve, I rage quit for the day. I finally figured it out, and raged back at my supplier on Google Reviews. They didn't like that, so they called me and they made good and credited me back some dollars.

I used my last 2 1/2 cans of R12 today and filled the system. Works great! Only thing is my compressor switches on and off during operation-- my guess is the pressure switch is keeping the high side pressure manageable. Either way it works great and I'm not touching it again.

dantheman67 · #12 08-14-2010, 08:20 PM

nope.

I didn't pull a vacuum test-- shame on me. There was a leak somewhere in the system. ALL my R12 is gone and I don't know where it leaked out from. I'm borderline depression... and I'm done with cars for today.

Anyone who's doing A/C restoration-- MAKE SURE your system doesn't leak prior to installing your valuable R12!!

dagObx · #13 08-15-2010, 12:25 AM

^^^ Yep, what he said...been there, done that!