I recently developed an issue with my 89 300e with aproximately 85k on the clock. The 1st issue is an unstable idle...not rough or surging just the occasional hiccup while idleing. I have also noticed that my ABS and Check Engine lights will occasionally go on during these idle hiccups. Performing a search these symptoms tend to point the finger at the OVP. I just came in from checking the OVP and the 10amp fuse is good. Could it still be possible to have a bad OVP and not blow the fuse or does my problem lie elsewhere?

Secondly my A/C has stopped working, for the first few weeks it would work occasionally but now it will not blow cool air at all. I do not hear the compressor cycling on or off but the blower motor works fine, and the refrigerant level is good. Since the problem was erratic early on I am hoping the problem is with the KLIMA relay. Is there any way to jump the KLIMA input pins to bypass the relay and see if in fact it is the KLIMA relay?

Thanks for your help,

Sam

The fuse seldom blows yet the OVP relay does go bad. I've replaced two so far.

Your ac problem may be in control module... behind the little temperature selector wheel. If so it can be easily repaired with a solder iron and a spot of solder. Look up my old posts to see how to do it.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

Replace OVP, it's bad, the contact are coming unsoldered. Typical failure. Check the fuel pump relay, too -- if it's hot, replace that before you start having stalling issues.

On the AC, check the belt. If it's worn, the compressor will slip and the KLIMA will kick it out pretty quickly. Also, jumper the wire from the top switch on the receiver/dryer, compressor should come on with ACC wheel set to full cold. If not, it's the KLIMA or the pushbutton unit, if so, it's low on freon.

Slipping belt will cause the KLIMA to kick out and refuse to switch compressor on until you shut car off and re-start.

Check the wires to the compressor too, it's possible, if rather unlikely, that the clutch wire is not connected anymore.

You can also jumper the clutch directly from the battery to test it, it may be faulty. blobs of sticky shredded rubber mean that the shaft seal is leaking and the clutch fell apart, too.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!