Air con slow to cool on passenger side
 

Hello all,

When I turn on the max AC or turn on the AC at any fan speed the passenger side does not cool as fast as the driver side. It takes 5-10 minutes before it starts blowing out cold air. I tested this multiple times with the same results. In fact, the driver side air is cooler than the passenger side when the AC finally starts kicking in for the passenger side. I went as far as turning the temperature 5-8 degrees lower on the passenger side with the AC on and the fan speed set at max. The driver side still blows out colder air. All the vents are fully open and air is coming out of all of them. The passenger side just takes longer to blow out cold air and when it does the air isn't as cool as the driver side. Any ideas?
I have a 2005 X5 4.4 with 53K miles.

Thanks in advance,
Benny

you need to check your evaporator. changing this is an expensive and labor heavy job

First check if the passenger side blows warmer with the A/C off and heater off (set to min temp but with A/C off). Could be that the heater valves on the passenger side are passing when they should be closed and re-heating the passenger side air when the A/C is on.

Also check that the cabin air temp sensors are not fouled with dust.

Also you may be low on freon. I know in my old bmw when it would get low it would cool the driver first then the passenger compart.

I had a similar issue. The rest of the a/c worked fine, but the right side vents blew warm air. Dealer ended up fixing a leaky high side service port for me under warranty and recharged the system. I have not had that issue since.

Brian, how do you tell whether the heater valves on the passenger side are passing when they should be closed? :dunno:

I think it's in his first sentence: First check if the passenger side blows warmer with the A/C off and heater off (set to min temp but with A/C off).

However, I just tried this and it didn't exhibit the warmer air. I had my temps set to 60, the ambient temp was about 75 and I had the AC off. The air temperature all the front vents seemed the same.

See my thread here for my ideas on the problem and some good feedback from other members:

http://www.xoutpost.com/bmw-sav-foru...ht-thread.html

As haigha points out - set both sides to min temp with A/C off and both vents should blow at about the same temperature. If the passenger side blows warmer - then the heater valve or the control signals to the valve could be the problem. See haigha's other post/link.

The valves are a simple 2 solenoid operation with one coolant inlet (bottom) and two outlets (either side - 1 for driver side and 1 for passenger side) The solenoid has a rubber seat inside the valve body which can perish and break up. The debris can either block the outlet flow to the corresponding side heater when its valve is open (resulting in no/little heat to one side) or the bad seat can fail to stop the flow to the heater when its valve is closed (maybe the latter in your case).

You can feel the temp of the inlet and outlet hose connections to/from the valve body to see if one outlet is warmer. You can check the signals with a voltmeter at the valves. I think the valves are energised to close and de-energised to open. When the required cabin temperature is reached, the valves pulse open/closed at a variable rate to maintain temp.

If you determine that one valve flow outlet remains hot when its solenoid is continuously energised then you can strip the valve body to try to resolve the problem (or buy a new one).

The heater valve is item 3 below.
Attachment 42346

Thanks for the additional information, Brian. I did some testing with my infrared thermometer--which I just remembered that I have-- and found some interesting data:

Around the heater valve, the hoses all were around 150 F.

With the air on for about ten minutes, the vents read:

driver left: 50 F, middle left: 64 F, middle right: 78, far right: 79

The last two are about the same as the outside temperature.

So now I'm starting to question whether my problem is the heater valve.

My BMW specialist made the same suggestion. He said sometimes getting a recharge would do the trick and if it doesn't he'll investigate it further.