ac drier
 

88 560sl. I have found why the aux fan is not working.The temp switch on the ac drier is bad.I need to know If I can unscrew the old switch and replace it with the new one with no loss of freon.does the drier have a check valve or such. thanks mike r happy thanksgiving:D

As of model year 1986, the temp switch has been replaced. A pressure switch is used to control the aux fan to safeguard the a/c compressor (S32). Additionally, in 1987, another switch was added to control the a/c clutch (S31/1). In either case, I think you are referring to the pressure switch (S32). It cannot be removed without loosing freon.

Why do you think the fan is not coming on, or better question, when do you think the fan should come on? Refer to the other post concerning the aux fan... The fan comes on ONLY if the engine temp exceeds 105C and/or the a/c drier pressure exceeds 20bar (about 300psi)... The two circuits are independant of one another.

Please refer to the manual, or the two attached links for further info. The wiring diagram attached to the other post on this board, clearly shows the two systems and how the fan is energized.

I don't doubt you can short wires and force the fan to work, as you are essentially making a switch that energizes the relay to turn on the fan.

Good Luck sorting out your issue...

http://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Climate/B.pdf
http://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Climate/C.pdf

http://www.peachparts.com/shopforum/mercedes-benz-sl-discussion-forum/284398-560-sl-electric-cooling-fan.html

dryer
 

Thanks for taking the time to help. Im getting on in years, awhile back fixing this would not have been a problem for me.
I noticed this summer,that when I first started the car in the day,the air conditioner put out plenty of cold air.when I would drive somewhere on errands when I returned to the car and started it,no more cold air, just slightly cool, not enough to cool :Ddown the car. that was when I noticed that the aux fan was not working.I wish you and yours a most wonderful holliday season. miker

as dryer
 

Hi,

Just a tidbit. My aux fan wouldn't come on either; so I wired the fan to a toggle switch on the dash so I can turn it on whenever needed. When engine temp gets high I simply flip the switch and fan is on. Easy job.

Good luck,
Joe R.
Millersville, Md.

Playing devil's advocate here...
Why? When is it needed?

Recall, the aux fan on the 560 is designed to only come on when:
1. The engine temp is above 105c
2. The A/C drier pressure is above 20 Bar (approx 300psi)

Be sure you are not masking a problem by treating a symptom, ie using the aux fan when other than designed.

To yours as well...
perhaps you can find a good indy to sort out your A/C. Check your fan clutch as well... Changed mine, even though I thought original was good, but, new clutch made a big difference...

R

ac dryer / rewire
 

Hi again,

The aux fan I rewired will work with both the auto switch and the manual toggle. Also it is on my 75 450sl whch runs HOT in the summer. Hope this clears things up.....

Joe R.

Yeah, I'm not as well versed on the older iron... Earlier models had a temp switch on the drier, IIRC.

If you are having heating issues in the summer, I suspect you have other underlying issues. These engines are not HOT until you see consistent temps above 105C or roughly 220F... It is quite normal for these cars to exceed 105 for short periods, but not get over 115C...

Glad the manual switch works for you...