I have a 2002 Discovery that blows good cold air from the two dash vents on either side of the steering wheel. It blows cool air from the two on the passenger side but noticeably not as cold as the driver side. I have pulled the glove box to observe the flapper box as I raise and lower the temperature on the passenger side but I think everything seems to be moving well. Has anyone had a similar experience? am I looking in the right place at the flapper box to confirm that the blend doors are fully moved to cold for the passenger vents? Can anyone point me to a diagram of the flapper box that has an explanation of what each of the doors is doing so I can better understand what I'm looking at.

 

Have you measured system pressures and temps? Colder air on one side (driver's) is often indicative of a low refrigerant charge.

 

Thank you for the response. I assumed if I had cold air I had a good charge on the system but maybe that's to simplistic a view. Can you point me toward what I should expect to see for pressure and where best to measure the temperatures. Thank you

 

I can tell you what you should do, and I can tell you what I'd do. First, you can take the truck the shop of your choice and have them put a set of R134 gauges on your AC system to check out system performance. They're more than likely going to tell you that you're low on refrigerant and then $100-$150 later you're going to leave there with a nicely working system until enough leaks out again that you're going to get warmer air on the passenger side again (unless they're the kind of jerks that will tell you that you need to replace a bunch of stuff that you don't need to replace). If you haven't serviced your AC in a long time and it's just now doing this then you probably have a minor leak and chances are you'll get a year or so out of it before the cycle repeats.

What I would do is drive down to the local version of whatever national chain you have is, and buy a $45 can of R134 with the little gauge on the top. Start the truck and turn on the AC then hook the can up to the Low ("L") side pipe up near the brake booster and see how much it will take before the little needle stops creeping up in between bursts. Follow the instructions on the can and do not connect to the H and do not turn the can upside down while filling. You'll probably get the same results as taking it to a shop without paying their diagnostic fee (hey, we KNOW you have a leak somewhere), and you may find yourself repeating this one or two more times before the can runs out. I am the last person to believe in magic bullets but I had to do this for the last year or two and this year here we are in mid-July and she's still running strong. Maybe their advertised claims that there are sealants and/or lubricants in there to restore the seals are somewhat truthful. Seems like they'll sell more cans if the system continues to leak though....

It's certainly possible that your flappers are leaking somewhat too but my guess is that your main problem is a lack of refrigerant.

 

I have added refrigerant in other cars so not a big deal for me to give this a shot and see if it resolves the issue. Thanks for the words of encouragement and a second voice echoing that a low charge can cause this problem.

 

Is the issue not blend motors rather than refrigerant?

 

i was wondering the same thing. however, blend motors don't seem to be a problem on these D2s like they are on the P38s.

how would low refrigerant cause the only one side to blow cool air? not being snarky. i genuinely don't know.

 

I can't give you the technical reasons (although I've heard it discussed here), but I can tell you from experience that for the last couple years this was how I knew the charge was getting low. So far this year I haven't gotten any complaints from that side of the truck and it feels as cold as the driver's side to me. It's certainly easier to blow $45 on a recharge attempt first than to tear your dash apart. I assure you, it's a thing.

 

The same happened to me a year ago. My wife kept mentioning she wasn't getting cool enough, but on the drivers side I felt great!

Topped off the refrigerant with a can from the local auto parts store and it is now much cooler on the passenger side. I'm not sure of the reasons for it either, but it worked for me.

 

Interesting.