560 sl climate control - PeachParts Mercedes-Benz Forum

mreddy · #1 08-22-2006, 01:49 PM

I recently purchased a 1989 560 sl. climate control seemed to work at purchase. Now, ac or heat will not come on automatically with climate wheel. Fan only blows if high or low buttons pushed. Also, even with fan button pushed, no cold air, and no real hot air, any ideas?

Lostyankee · #2 08-24-2006, 07:29 PM

Do a vacuum line check to narrow down the possibilities.
Do all your doors and trunk (matbe fuel hatch door too) all lock with the master or drivers door lock?
Are your power brakes OK?

Alkraut · #3 08-24-2006, 09:48 PM

Search the forum, there is lot's of information on this. Climate control issues are the most common problem with these cars. A few things to check: With Temp wheel on max AC and up/down button pushed check under hood to see if AC line gets real cold. If it does, life is good. It is located on drivers side along fender. Next go after the monovalve. They commonly fail at the seal and stay open, this allows hot water to get to system, even with A/C on. Again search the forum, as this is a relatively simple diagnosis and repair. Other issues are the pushbutton control box and the temperature sensor on the dash. The foam tube that brings air to the temp sensor usually is dry rotted away. Get to it by removing glove box, and work up toward center of dash. Easy to get glove box out if you know how to remove the four retainer pins and the light . You do not need to remove glove box door. The pusbutton units suffer most from solder joints that crack and cause opens. You can get a rebuilt unit, costs a bit. Last but not least is the temperature regulator which is a cigarette pack-sized aluminum box located behind the glove box. This controls the auto temp "logic". Hard to diagnose, but rebuilts are available. Good luck.

dpetryk · #4 08-25-2006, 07:42 AM

Often times the control module fails as a result of the infamous cracked solder joint problem. Resoldering the control module might bring it back to life.

david s poole · #5 08-25-2006, 10:55 AM

i think you have two problems.first i believe the heater valve/mono valve is defective which is allowing the heat to fight the cooling and in the summer guess which one wins.the second with airflow as has been alluded to is the push button control ground plane solder.this is not an emergency though as you have high and low fan.check the heater valve or block off the hose with a pair of needle nose vise grips you should get your cooling back. david poole dallas tx.

mreddy · #6 08-28-2006, 02:52 PM

Thanks David, still stumped, when I put the auto climate on I get no fan working at all, no heat or ac, when I use the fan buttons I get air moving but no heating or cooling just air.

appreciate the help'

Marty

mreddy · #7 08-28-2006, 02:58 PM

Also, with AC on max the compressor does not engage and lines do not get cold. all locks work with the vacuum system.
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david s poole · #8 08-28-2006, 04:07 PM

ok so now we have to assume that someone got it going in order to sell it. most common by far is out of refrigerant.if you look under hood in the front you will see aux fan and condensor. on the pass side of condensor is the drier with the low press switch[not the red fan switch with the short wires attatched] this switch has two male spade conns.if you take off the wires and electrically join them,then start car,put on max ac and look to see if compressor turning.let me know.