Yet another AC cold driver/warm middle/hot right thread

[haigha]

Originally Posted by m5james

RealOEM doesn't show actually pricing...expect more in the $300-$400 range. I've been able to disassemble and rebuild a few for customers over the years, but there have been some that deteriorated so badly that there was no saving them. These fail mostly due to people using the improper type of coolant, so sediment builds up and clogs up/deteriorates the seals within the valve...

Thanks for the tips.

The part pricing info is reasonably current on RealOEM for this (currently list is around $185). I found it at getbmwparts.com for ~$146.

I have never added or changed the coolant. It's supposed to be lifetime coolant in this vehicle (starting in MY04 for E53, IIRC). [ Edit: the coolant level and rating are checked at every service by my mechanic (roughly annually since I only put on 4k per year, last service in April 2010) ]

However, I'm wondering if it is the heater valve based on Brian's information in this thread:

http://www.xoutpost.com/bmw-sav-foru...nger-side.html

[m5james]

$385.52 for a new heater diverter valve for my 98 740iL and $176.98 for my 01 X...go figure the older car happens to have the more expensive parts

I just looked up the control valve for your 04 and I came up with $184.50. I'm going to open both hoods and take a look at the differences because I've always hated the idea of spending almost $400 for a replacement valve in the 7, yet they look so similar.

EDIT - I forgot the E38 has an integrated aux waterpump while the E53's is a seperate unit. Oh well...

[Rockmelon]

James, can this heater valve be bypassed to always get cold air? my winter here has higher temperatures than summer elsewhere.

[haigha]

Originally Posted by Rockmelon

James, can this heater valve be bypassed to always get cold air? my winter here has higher temperatures than summer elsewhere.

I considered the same thing as a temporary fix for summer and a way of testing whether you need to replace the heater valve before purchasing it.

I don't know what would happen if you capped all three hoses--the one into it and the two going out--simply removing the heater valve. It might not work though because the coolant could not flow properly

EDIT: Of course, I would never recommend capping the hoses and removing the heater valve from the system without consulting someone much more knowledgeable than me on HVAC

[Weasel]

Sounds to me like it could be one of two things... if it is the heater valve the AC itself is still cooling but the air is getting reheated. Usually when this is the case you can tell by seeing an extra high amount of condensed water dripping from underneath (compared to normal ac dripping) Otherwise this is exactly what happens when the charge gets low from a leak somewhere.

First course of action with ac problems is always to have the refrigerant levels and operating pressures checked. The E53 platform only uses 0.98 lbs of R134a so it only has to lose a little bit to do this. You should find a shop with a good "automatic" ac machine to recover/measure, vacuum, recharge to the proper amount of refrigerant. Hopefully that will get it blowing cold, but there will still be a leak to find. And unfortunately the evaporators do leak after so many years which can be hard to find.

[haigha]

Originally Posted by Weasel

Sounds to me like it could be one of two things... if it is the heater valve the AC itself is still cooling but the air is getting reheated. Usually when this is the case you can tell by seeing an extra high amount of..

Thank you for the great advice, Weasel. I'm going to my mechanic today to have him check the refrigerant levels. His AC equipment is manual but he does have many years experience working on BMWs (something like 30, IIRC). He'll be the first one to recommend going to place with an automatic machine if he can't handle it. The local dealer isn't an option since I can't get an appointment before my 1,200 mile trip.

When I talked to him yesterday morning, the first thing he recommended was checking the levels. I had convinced myself since we checked it when I was there in late April, it was still okay now. Especially after reading through the threads here about the heater valve and other issues. I'll update the thread after my appointment.

[haigha]

Update: I went to my mechanic and he added most of a can of R134a. He said that it's relatively common in our drier climate to need to add refrigerant every so often. He said that after 6.5 years adding this much is not a big deal but to keep an eye on it. He also said you have to be very careful not to add too much or it will make the problem worse.

When I used the infrared thermometer after it cooled down, the reading on the console vents was ~15 F

Total cost including refrigerant: $25
Having great folks at Xoutpost.com and a good mechanic: priceless

Thanks for the help everyone!

[tdgard]

Originally Posted by haigha

don't know what would happen if you capped all three hoses--the one into it and the two going out--simply removing the heater valve. It might not work though because the coolant could not flow properly

I have not looked at the E53 setup-but on my old E34 I cobbled those hoses together with fittings before they went into the regulator. This kept the coolant flowing but bypassed the heater core (which had blown out). You also need to disconnect any wires running to the valves.

[zzzzkev]

www.bavauto.com has part # 64 12 8 374 995 for $158.95.
They are in NH so no sales tax and generally ship for free on orders over $100.
I have used them many times and they are great.
Let us know how that works for you - I have a similar issue with my '02 3.0i

[Weasel]

It is still more likely to be a low charge, and it would make sense to check that before throwing parts at it as the heater valve is only the problem 5% of the time at best.