Heat issues with 89 300TE
Thread Starter
Member
Joined: Jun 2004
Posts: 159
Likes: 6
From: BC, Canada
2007 ML350 (M272) 30-509034 & 2008 ML320 CDI
Heat issues with 89 300TE
Keep the problems coming...Last night was a little chilly driving home so I decided to turn the heat on for the first time in my recently purchased 89 300TE. Well the heat was cycling on and off in the car whether I had the upper and lower vents switched or just the lower, even with defrost as well. With both the high and low fan speed setting it was doing this. The only time it does not do this is if I put the switch to EC (economy). Not only was it cycling but with the window down I could hear a noise coming from my engine in sync with the heat going on and off. I just checked it and it sounds like a pump clicking on and off or intermittent whirring almost. When I rev'ed the car up to about 4000 RPM, the whirring noise is insanely loud!! I have attached a pic of the area where the noise is coming from. Is this caused by the A/C pump/compressor and if so, why would it be doing this with the heat on? Any ideas? Damn this car! LOL 
Super Member
Joined: Jun 2003
Posts: 595
Likes: 0
From: Middlefield, CT
1994 E320
Buried in the dark in that pic is the compressor. If the climate control is set to 'EC' the compressor should NEVER engage. If it does the climate control pushbutton unit is very likely screwed up. You can get rebuilt units online for a lot less than new.
Thread Starter
Member
Joined: Jun 2004
Posts: 159
Likes: 6
From: BC, Canada
2007 ML350 (M272) 30-509034 & 2008 ML320 CDI
The compressor does not come on when ED is pressed. However, it comes on with every other button. Should it with the heat on? I thought it only came one with the A/C? Also, should it be making that horrid loud whirring noise? Would it be the bearing in the compressor or? It's a harsh noise and very loud and noticeable while driving.
Super Member
Joined: Jun 2003
Posts: 595
Likes: 0
From: Middlefield, CT
1994 E320
With the automatic climate control you can't turn on/off the heat or A/C independently like in a manual system. Depending on the air temperature inside the car and the setting of the temperature wheel, the A/C and heat will be throttled automatically, and sometimes mixed.
The compressor should be quiet; it does not make much noise. Yours is probably baked. You can get a rebuilt unit. Just make sure everything is intact, including the Nippondenso plate, otherwise you will not get a refund on the core!
The compressor should be quiet; it does not make much noise. Yours is probably baked. You can get a rebuilt unit. Just make sure everything is intact, including the Nippondenso plate, otherwise you will not get a refund on the core!
