my car is a euro 1989 s124 300td. I have a rotary type aircon. Sometimes, when I start the car, the compressor does not want to turn on. When I try to push the buttons - central vertical row of 3 pushbuttons (demist, air-con compressor enable/disable, recirculate mode). They don't respond - the lights don't go on or off. So, if normally the middle - compressor button is lighted, even if I push the switch, it doesn't want to turn off.

If I turn off the engine and leave it on ignition (before starting), the buttons respond well. However, as what happened earlier, after restarting the car, the compressor is still off. It finally turned on after driving the car for about 10 mins.

Also, sometimes, the blower, when positioned at #1, wont turn on instantly. #2 onwards turns on instantly. Left at speed #1, the blower will work after a few minutes.

I've also experienced the reverse. The compressor is on, the switch is on, but when I try to turn it off, the switch would not respond as well

What could be the problem? Please help

Also, I've replaced these items related to my a/c already about 6 months ago -

compressor
aircon blower
aircon blower switch
evaporator
dryer tank
expansion valve
dryer
fuses

First thing to do is remove & clean the 2 fuses that control the a/c system.

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intermittent blower speed issues point to current issues. You either have a dirty/failing commutator and or brush, OR a loose connection downstream of the switch. Check your fuse box as suggested...

drop by the house let's troubleshoot...bring the snowtires while you're at it.

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85 190E 2.3(SOLD)
86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
87 300TD (SOLD)
95 S280 "The KRAKEN" (Turbo 2.9 602 transplant) traded
86 190E 2.3... current project

I already replaced the fuses. I dont think its the commutator brushes. Blower is new and the blower is not my main problem. It's the a/c compressor (turning on and off of it)

@locry. Sunday?

Next time, try rotating the ignition switch slightly counterclockwise.

The switch can get sloppy and have intermittent contact.

Jim

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@Jim- I tried that already. Also, the blower works. It instantly turns on for speed #2,3,4. For speed #1, sometimes there is a delay. I think it turns on together with the compressor.

However, that is not my main problem. My concern is mainly on the 3 vertical switches. It gets "stuck". If it's on, it does not want to turn off - the red light will stay on and vice versa. However, the compressor will not follow the state of the switch. The switch might be on, but the compressor's clutch doesn't want to engage

I was fiddling with it yesterday. Sometimes, if I press long enough, it turns on /off.

ok, follow up question...for general clarification...
Is there a switch/control module that tells the compressor NOT to engage when the engine has not reached a certain temp?
Because my compressor will not engage immediately after startup. It WILL engage after a few minutes when the engine has warmed up. This leads me to believe that engine temp is a variable. (is this always the case... and i'm just not familiar with it?... hehe)

__________________

85 190E 2.3(SOLD)
86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
87 300TD (SOLD)
95 S280 "The KRAKEN" (Turbo 2.9 602 transplant) traded
86 190E 2.3... current project

No, the compressor does not wait for a particular temperature before it starts to operate.

I'll quote from another post -H ere are some of the controls of the klima relay -
(1) when the engine is started, the relay keeps the compressor solenoid off until 10 seconds after the engine speed has reached 600 RPM. This "improves engine speed stabilization after startup."

(2) with engine speed less than 1050 RPM, when the accelerator is floored, the compressor solenoid is released until the engine reaches 2150 RPM or the accelerator is released. This function is controlled by a microswitch on the valve cover (I thought that microswitch was the kickdown switch -- it is not).

(3) if freon pressure is lost, a pressure switch tells Klima to turn off the compressor solenoid, saving the compressor from damage.


I'm starting to think my problem is the a/c control module after reading this post. Either that or the klima relay. Hmm...

I'm just wondering why I have not seen the same symptoms from another user in reading the forums

deym! then I have issues as well! my compressor only kicks in well after 10 seconds... even a minute maybe. It will NEVER engage in less than 20 seconds when started first thing in the morning. It will sometimes engage immediately though when activated sometime during the day. This happens MOSTLY after sitting the night... s'why i concluded it be a temp thing.

__________________

85 190E 2.3(SOLD)
86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
87 300TD (SOLD)
95 S280 "The KRAKEN" (Turbo 2.9 602 transplant) traded
86 190E 2.3... current project