A/C - help trouble shooting, fixing

[GreenMedallion]

Hi all. I searched and searched, but could not find the right answer (not to mention when I search for "A/C" or "AC" no results show.)

My 1979 300TD n/a wagon has never, since I've had it, had a working A/C. Heat blows great, and blows well on A/C settings "hi" or "low" but nothing cold. Orig. owner mentioned the system needs to be recharged. If that is all that needs to happen, is there some way to confirm that it just needs to be recharged, short of just recharging it?

I also notice the following when I put the A/C "on". The fan blows well, but when I push the "on" button for the A/C, and hold it in, some other fan kicks in, but does not stay on when I am not holding down the "on" button. Is there something wrong with the switch? Or bigger problems?

I am trying to sell this wagon, but if I get the A/C working, may just hang on. Reason for selling - moving to very humid climate where A/C will be a necessity.

Thanks.

[vstech]

search and read all threads titled evil servo.
it's good your settings work in heat. and the fan works. does any air blow out the center vents when you set it to A/C and have the dial set to min?
if not, go back to checking the evil servo threads.
I had a 79 TD. fun little car. never got the A/C working.

[GreenMedallion]

Thanks, will read the evil servo threads.


To answer your question - Air does come out the center w/ AC on.

No dials on this one - my climate control looks like this -

[colincoon]

Read all of this:

http://www.peachparts.com/shopforum/showthread.php?t=240530

[79Mercy]

OT: but wow thats the first diesel other than a coupe(300CD) i have ever seen with burl wood.

What is your VIN number?

[GreenMedallion]

Sorry, not a pic of my interior, just found online for convenience.

From this page - http://commons.wikimedia.org/wiki/File:Climate_Control_MB_w123.jpg

Looks like it was uploaded from Germany, so possible a motherland-only special?

[79Mercy]

Burl wood came on some early gasser W123's and on some early diesel coupes.

[GreenMedallion]

Funny - I just noticed 79mercy and colincoon are in FL. I am hoping to get the AC working as I may be moving from Los Angeles to St. Augustine later this year.

Any chance you guys know a good MB mechanic in those parts?

[bobodaclown]

pierre

[vstech]

... that dial on the left side of the vertical buttons... blue numbers are cool. should have a min setting.
it's a very good sign that you have air out the center vents. your servo appears to be working. I'd have the system leak checked, and possibly, just head off issues, and replace the expansion valve, and charge it up and see if the compressor cools!

[69shovlhed]

does the compressor clutch lock up when you turn on the ac? you can't trouble shoot it if its empty. evacuate and charge the system w/ r134. all you need are the adapters to do this, don't let the shop tell you that you need all this new ****. have them put some dye in it so if there is a leak it will be easy to find. if you fill it and it works, done deal. if it don't work, put 12v straight to the compressor clutch to see if it will lock. don't leave it jumped for more than about 15 seconds, unless you have gauges hooked up, pressure can go way too high if there is a restriction.

[leathermang]

DO NOT PUT DYE INTO YOUR AC SYSTEM.
It can stop up the Txvalve and other small stuff..

AND

it will NOT HELP YOU FIND A LEAK IN YOUR EVAPORATOR....
Just say NO....

There are HUGE numbers of good threads which tell the proper way to do this stuff....
if it is probable you have a leak there is a legal way to check it.. in the archives available by using the search feature...

[69shovlhed]

Originally Posted by leathermang

DO NOT PUT DYE INTO YOUR AC SYSTEM.
It can stop up the Txvalve and other small stuff..

AND

it will NOT HELP YOU FIND A LEAK IN YOUR EVAPORATOR....
Just say NO....

There are HUGE numbers of good threads which tell the proper way to do this stuff....
if it is probable you have a leak there is a legal way to check it.. in the archives available by using the search feature...

bs, dude. at the dealer, we put dye in every ac system we serviced, and i mean every single one with no problems ever. it is the easiest way to find a leak, and if its the evaporator, you can smell the r134 inside the car. just get the evac and recharge done w/ dye. no need to flush unless the system was left open for years or the compressor grenaded. no need to replace expansion valve unless its bad, and you don't know that yet. any time we got a car at the dealer not cooling, if its too old to get codes out of it, hook up the ac machine and check pressures, no pressure, look for obvious leaks, ie. hoses soaked in refrigerant oil. no obvious leaks, evac and recharge. retest system, verify compressor clutch locks, check pressures, check temp at vent. r134 isn't too expensive, r12 is very expensive now.

[leathermang]

Originally Posted by 69shovlhed

bs, dude.

With me quoting AC industry wide accepted logical frugal advice based on the MERCEDES FACTORY SHOP MANUAL and the EPA rules and sites like Aircondition.com and ACkits.com and three Air conditioning manuals used in school training classes you start your reply with that...

I admit that aside from your total lack of regard for anything except your time in relation to the flat rate manual that there is clearly a generation gap shown by your attitude and writing style.

That was interesting that you would falsely assume that using Nitrogen and R22 would be a time consuming process when in fact it is almost instantaneous read at the vents with the electronic sniffer. Also, your willingness to ignore your customer having to return later if the refrigerant leaked out.. .at which point you were in the same situation as you started EXCEPT for the LOSS of the refrigerant... but you consider the fact that you do not charge for the second evacuation and charge the redeeming fact.

I have to thank you for being so honest in your answers... you have volunteered way more than I could have ever hoped for in pointing out the difference in value judgments between Owners taking care of their own prized cars and the potential for ' values' other than long range reliable and frugal service to be applied to those cars.... the FLAT RATE MANUAL and its relationship to YOUR paycheck being the obvious one highlighted by you, 69shovlhed.

I have admitted before that I have a bias towards knowing and following the rules. From 18-22 I was an Army Aviator flying a UH-1H Huey including all of 1969 in Viet Nam. Part of that year I was the night test pilot in the maintenance section. Since 1980 I have had my Permanent Peace Officer license in Texas and have worked as both a Deputy Constable and Deputy Sheriff at various times. I have been a welder and farm mechanic for years... So knowing and following the rules in my life could have made the difference between being here and NOT... I am proud to say I have vision in both eyes and all my fingers and toes intact and am mobile.... so you lose on the ' office ' bet. And in 74-75 era I rode my new Superglide shovelhead to SWT in San Marcos from Austin before transferring to UT Austin....

[GreenMedallion]

Here is what seems like a good game plan -

1) evacuate/flush system
2) replace expansion valve
3) recharge w/ Freeze-12
4) hope I get cold air!

Since I am pressed for $$, would there be any harm in skipping 1+2 and just trying to recharge the system? Would be only possible loss be a few cans of Freeze-12, or would that cause other damage?