First Day of Summer - AC Woes

[tankowner]

Hello All:

It been getting rather warm here lately and my AC is not cutting it. It's only moderately cool (~60 F) out of the driver's side vents, but blowing warm air out of the passenger side vents. I'm wondering if anyone has experienced this before (cool out one side, hot out the other) and what the cause was.

A little background. The truck has had a slow leak the past few years - meaning I would add a little refrigerant when it started warming up, and then it would be good the rest of the summer. I do have a manifold gauge set and use it to try to diagnosis problems. The past couple years when it wasn't cooling adequately, I would hook up the gauges and find both the high and low pressure side to be a little low, suggesting it just needed a recharge. Adding some refrigerant would cool it down.

This year is no exception, both high and low pressure gauges were reading a little low, 20 psi and 150 psi, respectively. I've added some refrigerant to get those pressures up to around 35 psi on the low side and 185 on the high side.

I also added some dye to the system to inspect for a leak. Unfortunately the UV light hasn't turned up and leaks that I can see. I also purchased a halogen sniffer to investigate for leaks in that manner, too. Although, again, I've yet to find a source for a leak.

Once I added the refrigerant today, the driver's side starting cooling down to around 60 degrees. As an interesting note, the condensate drain tube on the driver’s side was dripping lots of water. However, the tube on the passenger side was not dripping at all. I'm not sure how meaningful that might be since I'm not exactly sure what the evaporator drain system looks like.

At any rate, just wondering if anyone has any insight on what the problem might be. Thanks in advance for any responses.

2001 (E53) X5, 3.0

[upallnight]

Put the sniffer in one of the ac vent. You could have a leak in the evaporator inside the car.
What was the outside temp when you got the 35 low, 185 high side reading? Was the aux fan running anytime you had the ac on?

[tankowner]

Originally Posted by upallnight

Put the sniffer in one of the ac vent. You could have a leak in the evaporator inside the car.
What was the outside temp when you got the 35 low, 185 high side reading? Was the aux fan running anytime you had the ac on?

I did try the sniffer at the AC vents yesterday but wasn't getting any hits. That was right at the louvers though and I suppose refrigerant from an evap leak may be too diluted at that location. I will keep trying there.

The temperature was around 85 F when the 35 low, 185 high readings were taken. This morning the external temp. was 74 F and it was blow 40 degrees out of the far driver's vent, 50 out of the central driver's vent, 60 out of the central passenger's vent (I'm not sure about the temp out of the far passenger's vent because I couldn't reach that far while I was driving - but it was undoubtedly the warmest).

Yes - the aux fan does cycle on and off while the AC is on and the truck is parked.

Thanks for the feedback. Of course, no one ever wants it to be the evaporator, but if it is, I'd like to confirm it somehow before tackling that job.

[upallnight]

There are mixing valves for the heater core and perhaps one of the heating valves is not closing. Do you have the auto or manual climate control panel?

[tankowner]

Originally Posted by upallnight

There are mixing valves for the heater core and perhaps one of the heating valves is not closing. Do you have the auto or manual climate control panel?

Thanks - that a good point I hadn't really been considering. I have the auto (push button) climate control panel - like the one in the picture below.

[Zulu95]

Having read this report many times and experienced it once you have cured the symptom of low refrigerant but not the reason as to why it is/was low. Try sniffing around your high and low service ports. Our '01 needed the port seals done 10 years ago. The kit supplied by the dealer was reasonable and updated the valves to the common type found in most modern systems that can have the "O" rings replaced as and when required. If it is not a service port problem then it could get expensive in a hurry.

[tankowner]

Originally Posted by Zulu95

Having read this report many times and experienced it once you have cured the symptom of low refrigerant but not the reason as to why it is/was low. Try sniffing around your high and low service ports. Our '01 needed the port seals done 10 years ago. The kit supplied by the dealer was reasonable and updated the valves to the common type found in most modern systems that can have the "O" rings replaced as and when required. If it is not a service port problem then it could get expensive in a hurry.

Thanks Zulu - good point and I forgot to say that I have indeed replaced the service ports already, fearing that they could be the source of the leak. As you point out, it's a cheap insurance measure when troubleshooting, so I just went ahead and replaced them. I can place the sniffer in the ports to check, the problem yesterday was that I had just recharged the system so there was refrigerant present within the port which the sniffer was excited about. I get no indication around the outside and base of the ports, though. I will try inside the ports again today, maybe with enough time the refrigerant dissipates at the port entry. For the record, I changed the entire port and not just the schrader valves.

You are correct, though, recharging is just a stop-gap and not solving the problem. I'd like to find the source of the leak and also resolve why the driver's side blows cold but the passenger side blows warm.

Thanks!

[Zulu95]

I have read that the driver's side cold, passenger side warm is some sort of fail safe to ensure the driver gets the cooling as long as possible when there is a problem until it fails completely. There was a long discussion on this on a board a few years ago. I know the last time I had it happen a quick charge cured the problem and no leaks were found so I guess it may have been a SP seal.
It's so darned hot at present I hope you find the solution as cheaply as possible.

[tankowner]

Originally Posted by Zulu95

I have read that the driver's side cold, passenger side warm is some sort of fail safe to ensure the driver gets the cooling as long as possible when there is a problem until it fails completely. There was a long discussion on this on a board a few years ago. I know the last time I had it happen a quick charge cured the problem and no leaks were found so I guess it may have been a SP seal.
It's so darned hot at present I hope you find the solution as cheaply as possible.

Wow, that would be bizarre if true, but I almost don't question it based on the over-engineered approach to a lot of BMW features.

So you've had this same problem before - with the cool air on the driver's side and warm air on the passenger's? And you recharged and it resolved the issue? Because I had the same issues the past year or two and it seemed like the simple recharge mostly resolved the cooling discrepancy between the two sides. I guess my concern right now is not overcharging the system. Do we know what BMW specs for the high and low pressures on this model? I've looked around but haven't found anything real definitive. Some have said the low side range should be between 25 - 35 psi.

Yeah, the past few days have been a little uncomfortable. And the hotter it gets outside, the less the AC wants to cool.

[upallnight]

Originally Posted by tankowner

Wow, that would be bizarre if true, but I almost don't question it based on the over-engineered approach to a lot of BMW features.

So you've had this same problem before - with the cool air on the driver's side and warm air on the passenger's? And you recharged and it resolved the issue? Because I had the same issues the past year or two and it seemed like the simple recharge mostly resolved the cooling discrepancy between the two sides. I guess my concern right now is not overcharging the system. Do we know what BMW specs for the high and low pressures on this model? I've looked around but haven't found anything real definitive. Some have said the low side range should be between 25 - 35 psi.

Yeah, the past few days have been a little uncomfortable. And the hotter it gets outside, the less the AC wants to cool.

System pressure is NOT the correct way to recharge an AC system. The correct way is to remove all the refrigerant from the system and refill base on the the weight of refrigerant as measured with a digital scale. That is why there is no BMW specification for system pressure.

Here's a youtube video on the correct way to charge an ac system.

https://www.youtube.com/watch?v=4n5UKTXNyGU