my heater blows ice cold air on.... the climate control switches air between floor and dash vents properly on automatic mode, but the air is ice cold. i have the temp on full heat but i get only ice cold air.

anyone having this problem.

thanks

I have the same problem but after the car is running for 10 minutes or so the problem seems to goes away.

Jim

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2005 C240 4matic wagon (daily driver)
87 190D - 225K (on loan)
85 190D - 312K (on loan)
2011 Subaru Legacy AWD (Wife's)

Does this model have a monovalve? If so, symptom is typical of a failed monovalve.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

You need heat in Hawaii???

If you have a monovalve, then take off the electrical connector and see if it gives you heat. If so then you can rebuild the monovalve.

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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

If you have a failed diaphragm, you may not get heat, whether voltage is applied to the monovalve, or not.

Therefore, this test is invalid as conclusive evidence of a bad monovalve.

If the vehicle has a monovalve, the recommendation is to simply remove the top and check the diaphragm. It's a 10 minute job.

Well yes you are right, I guess I was assuming that the diaphram is good.

Boy I am glad you are right there behind me. I need to quit posting at night when I am dead tired.

__________________
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

....

i will remove the top and take a look... but wouldnt the air be at least ambient? its ice cold... i was wondering if my climate control wasnt diverting the air through the heating coils.

i will check out the mono valve first thing

oh and yes we do enjoy some heat at times even here in hawaii

thanks for the input guys

Only if you are up near the top of Haleakala, bra

Check to see if your A/C compressor clutch is activated when the cold air is blowing instead of heated air. Make sure you are at operating temp.

How much does your diesel cost on Kauai?

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You can get farther with a smile and a gun than you can with just a smile.

1984 300D
1985 300CD
1980 300SD
1993 SL500

yeah the engine temp is at 90 but only cold ac air blows when i lock the heat setting to max heat. i set it to defrost and only cold air blows on the glass. the ac compressor is on when i have it in heater mode. monovalve notwithstanding, the compressor shouldnt be running when i select heat right?

oh and diesel is a rip on kauai at $3.30. i can get bio-diesel shipped in from oahu for $3.00 --- off road grade , but there is a waiting list. i read one thread that this guy was buying veg oil from costco and using it svo in his car... isnt it too thick? i dont think its cost effective (excluding environmental cost) until diesel hits at least $5.

mahalo

"the compressor shouldnt be running when i select heat right?"
If your CC has a EC( economy) setting, that should be where the controls should be set for max heat. Any other CC setting will run the AC compressor , if the ambient is above 36º.

hmm... thats odd, i used to get heat when i hit the defrost button or the dash vents... its an automatic climate control... as long as the temp is set to heat, heat should flow i am assuming.

i will check on that setting; however and see what i get..

thanks

Just discovered the misterys of the mono valve and heating problems. Just un plugging the connector from the mono valve will not check its operation if the internal rubber membrane is torn or has a hole in it because the membrane actually builds pressure on it when the valve is in the closed position ,and needs this pressure to help open the valve when the valve is denergized(turned off). But the good news is that you can fix the membrane very cheeply if you want to. I just fixed mine by cutting a new rubber disc from a bicycle inner tube and used it to replace the membrane. It works GREAT! I now have heat again.

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You have to "un stake" the bottom washer of the valve, remove it, install your new sheet of rubber, and " restake " the washer back on with a small punch. I then glued the rubber to the old membrane where it wraps around the valve to make a seal. after it dries, you can trim the edge with sizzors and reassemble the valve. I am trying to add pics because it is hard to explain without them.

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The test is a lot more valid if you change it up a bit. If you remove the electrical power and you do get heat, the monovalve is reasonably excluded as the problem. No heat points to the monovalve as the problem.

A common symptom of a torn diaphragm is that the heat works well at low engine rpm, but not at highway speeds. Stop at a red light and the heat comes back on.