I have a 1995 E300D. Sunday morning I drove to Pep Boys to buy some car wash and misc. items to clean the car. The air conditioning in my car was working fine. The system used to blow cold air in traffic and the aux fan ran properly to keep things cool.

While at Pep Boys I saw some engine cleaner. Got home and washed the car. About an hour later I popped the hood and proceded to spray the orange smelling gunk on the engine. I rinsed off the engine with water. Then I turned on the engine. I sat in the driver's seat and noticed that the A/C was not cold. Then engine ran for 5 minutes or so, still no cold air. I drove up the street thinking that perhaps the aux fan fuse was bad...so that the aux fans were not coming on. When that happened before at highway speeds I would get cold air. This time nothing. Returned home and checked the fuse in the aux fan relay, it was fine. I turned the A/C on and off....the compressor engaged and disengaged fine. I shorted the two wires going to the low speed fan sensor (on the dryer) and the low speed fans came on....but did not come on otherwise.

What happened? It must be related to cleaning the engine...but how? The AC compressor still engages. With the air moving across the condenser I'm still getting warm air.

Maybe then engine cleaner got between the friction contact surfaces on the compressor clutch? The cluth would engage but maybe it's slipping and not actually turning the compressor. Can you see refrigerant movement in the sight glass? Is the condensor warm?

Washing modern engine bays with water is not a great idea.

By now it should have dried off and if it still doesn't work you may have problems that are coincidental

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

I can see movement in the sight glass. I dropped the car of to the mechanic tonight. It will be interesting to see what they find. Seems like the dreaded evaporator failure would happen over time?

I'm also having the glow plugs done. When it rains it pours.

Tech found that the A/C needs a recharge, should know more soon...when I called they had not yet injected the dye to look for leaks. Still doesn't make sense to me though since the car was blowing cold in the AM. Also the low speed fans didn't kick on (like the usually do) when the AC was turned on. Perhaps because there wasn't enough pressure at the switch? Hmmm.

And the glow plugs are fine...problem is with the relay.

It could be that the sensor finally decided that this was not enough. It might be teetering on the edge and something drove it over the edge.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Well they charged up the A/C and they've been watching it. No leaks...and now the aux fan kicks on. I guess there wasn't enough coolant in the lines to build up the pressure. Looks like cleaning the motor and the A/C failure was a coincidence.

In other news they replaced the glow plug relay, then found 4 bad glow plugs. The pulled the intake manifold to replace them...well aware of problems with OM606s and glow plugs. They wouldn't budge. They going to soak them down with penetrating oil and try again in the AM.

This morning the glow plugs turned but are stuck because of the carbon deposits. More soaking and wiggling over the next couple of days...hopefully they will come out without breaking!

The low pressure switch was probably cutting the power due to low psi. Very weird that it happend when you washed the engine....

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Had the same problem with my 92' 300D. Got in my car and drove to a friends, left a couple of hours later and it blew nothing but warm air. Turns out the evap. coil had a slllllooooowwww leak and finally leaked all out. The problem was that, at first, we just thought it needed a charge of freon so we had it filled up and it ran good for a few days/week and then it all ran out again (became a much faster leak). Anyway, finally had to replace the evap coil and traditionally that aint cheap... but have a mercedes mech. in the family. Anyway, hope your problems fixed! Those things are famous for going out around the 13th-15th year.

Yeah I know. Each time the mechanic calls with an update I tell him...don't tell me it's the evaporator!

Of course now with the glow plugs stuck in the head I'm fearful that he's going to call and say that one or more snapped...