E53 climate control AC problem - Need help!

dougal · #1 08-13-2019, 01:37 AM

Hi all, yet another problem on my E53 but this is one I REALLY want to fix because our summers (Malta) are hot and it currently 36-38C temperatures outside.

Sooo, up until last Saturday the AC was working perfectly... Ice cold.. lovely.

Then Sunday night went out and it was very humid and the AC was barely keeping up.

Yesterday (Monday) morning the AC worked fine on my way to work but afterwards during the day it was only sort of cooling, just about "OK".

I went to an AC shop and they checked the refrigerant but said it looks fine but to make sure they drained the system and refilled it with the recommended (i think 440grams) of R134a but it did not make any difference.

The compressor turns on, the AUX fan is working fine and there is R134ain the system and does not appear to have any leaks.

So the symptoms seem, the AC sometimes works nice and cold, sometimes its "OK" (tolerable) and sometimes hardly. What I noticed yesterday is that the air from the passenger side (its a right hand drive car) air vents is cooler than the driver side vents.

I plugged the an Autel diagnostic scanner and whilst it found no issues with the HVAC/AC system it did report that while the left heater core (i think) was 20C the right side was 25C.

I am told (on XOutpost E53 Facebook group) it could be the Heater Valve Control located near the shock tower. Ok, that would be great if its just that and it can be replaced quiet easy and cheap but how can I be sure before shelling out money on a new one ?

Can it be bypassed temporarily just to test if the AC issues get solved ?

Another issue, don't know if its directly related but the blower seems to be blowing not as powerful and this exactly the same time I got these AC issues.

wpoll · #2 08-13-2019, 03:45 AM

Here's the heater core valves you're looking for...

https://www.newtis.info/tisv2/a/en/e...ntrols/OSXDECV

EODguy · #3 08-13-2019, 07:14 AM

"Can it be bypassed temporarily just to test if the AC issues get solved ?"

Yes, quite easily pull the hoses off both sides at the valve and use an appropriate sized plug. (I used old spark plugs as a fix in the desert)

Also 38c? I'd have to wear a coat!! I've been stuck in the Middle East for 11 years and once you've lived through 60c summers... Well let's just say changing hot horseshoes has to be easier than holding a steering wheel

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andrewwynn · #4 08-13-2019, 12:19 PM

If you can access enough length of hose just clamp the hose off. Their is a to for that (you can even clamp off radiator lower hose to change a radiator without draining block). You can use a locking needle nose pliers with a couple pieces of wood to protect the rubber.

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