Heat only coming out of drivers side - BMW Forum

Yankees368 · 10-25-2005, 12:00 AM

For a little while now, I am only getting heat out of the drivers side of my E34 (1994 525i). The drivers side heat works fine, but no matter what temp setting the passenger side is set to, it still blows cold air. I took off the temp knob to see if the it was accuratly turning, and it is. I do have the hot/cold controller set to hot.

Someone please help me out here, it's cold in buffalo!

///Matt · 10-25-2005, 10:55 AM

I have had the EXACT same problem on my 5...I ended up having to replace the heater pump and that did the trick. Once removed, I saw that the pump had completely failed on one side and that the gaskets were completely rotted out. Check your pump and see if it needs to be replaced, mine cost about $160 to R&R.

Yankees368 · 10-25-2005, 11:06 AM

This would not have anything to do with the water pump, would it? We just had that replaced. Also, did you go the service yourself...or does the $160 include parts and labor?

///Matt · 10-25-2005, 05:08 PM

Ok, I think I've narrowed it down...

Inspect your heater valve which looks like this...

It should be on the driver's side near the back of the engine compartment and will have a lot of tubing going into it...Remove it (dont forget to clamp off the hoses so you dont lose all your coolant) and inspect. Bavarian Auto sells a new one for 139.95 (64 11 8 391 417) and this is a pretty easy DIY.

Yankees368 · 10-25-2005, 08:20 PM

I really dont know anything about what goes on under the hood, how much would this run me to have a pro do?

///Matt · 10-25-2005, 11:05 PM

A BMW center running about $100 per hour, will probably charge an hour of labor. However this is a very simple fix. All you have to do is unplug the wiring to it, use clamps on the hoses, take out the valve, put in the new and replace the hoses and wiring plug. But I can understand if you want to be absolutely sure by going to a pro. This is something that any mechanic can do...

Yankees368 · 10-25-2005, 11:43 PM

Maybe i will get down and dirty and fix this myself. If this is as easy as you say it is, I should be able to do it myself. By the way, the local BMW dealer charges $175 hr.

///Matt · 10-26-2005, 10:53 AM

Your dealer charges $175...WOW! That's the highest BMW price i've come across...

Yankees368 · 10-26-2005, 11:12 AM

Welcome to Long Island...

sp0rky · 10-26-2005, 03:59 PM

its likely the heater valves, and they are rather simple to replace since they are right on top.

good luck

soloextreme · 10-26-2005, 04:01 PM

wow....im new here, but have been around forums of all types for years now and i believe matt's post is one of the most helpful posts i have seen in a while. great job. posting pics and everything.

Yankees368 · 10-26-2005, 04:32 PM

Ok...somebody figure this out.

I turn on the car today, and the heat is working both sides full blast!

What is going on here?

sp0rky · 10-26-2005, 11:24 PM

the heater valves are mechanical.

Often, "sludge" from dirty / old coolant clogs and they either can not open or stick closed or open, etc.

A lot of times turning them on and off enough times can temporarily (if your lucky, permanently) dislodge the sludge and restore normal operation.

Aside from that, sharp bumps, jolts, etc can help it and sometimes it's just pure luck.

It's very possible that one or the other will jam again, but if not - glad to hear that your luck worked out.

Yankees368 · 10-26-2005, 11:45 PM

Well, lets see how long it stays working for!

crgrbrts · 12-06-2005, 01:12 PM

Warm thanks to Matt! I was also having the "heat only out of the driver's side" problem (much to the distress of my much chilled wife on the passenger side). After consulting this forum I located my heater valve, gave the right side a sharp "thwack" with my genuine BMW/HEYCO reversible blade screwdriver, and am now enjoying a fully heated cabin. If the problem recurs, I plan to remove the valve and clean it. I would think carb cleaner would do the trick (though I don't know what's inside).