01 540i/6 AC a little warmer on passenger side

[M5XTu]

When I turn my AC on at coldest setting (60F), I noticed that the passenger side is a little bit warmer despite the temp set at coldest. I replaced the heater valve with a used one but still the same.

Could the used replacement one also be bad? Any other part I should look into?


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[jai5w4]

Just noticed this on mine as well. I'm told a can a freon and a quick top-off will remedy this. My folks' X5 had the same issue and that fixed it. Gonna try it on my car next.

[dannyzabolotny]

Chances are that your replacement heater valve isn't good either, especially if you got it at a junkyard. The only way to fix the problem 100% is by either buying a new heater valve ($$$) or rebuilding a used one using one of the many rebuild kits available for it. It's very common for them to fail, especially in Phoenix where a lot of idiots put tap water into their cooling systems— the hard water here builds up some nasty deposits in the cooling system and heater valve.

If the air is blowing properly cold from one side then that means the AC is working fine, so I wouldn't worry about that. If rebuilding/replacing the heater valve doesn't work, a possible cause could be a stuck blend flap on the passenger side, though I can't say I've ever really seen that happen on an E39.

[draztike39]

Had the same issue. Charged freon on it and it went away. Been working good since then.


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[54ODell]

Thanks for topic. Same issue here. I'll try a recharge.

[M5XTu]

I had my AC pressure checked. As it turned out, I only have 1/2 pound of freon left. Not enough to even turn the aux fan on high mode. Shop refilled. All is good is now.


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