Hey,

My truck, which I have owned since new (10 years) has always had excellent a/c. Cold all the time, never had to do a thing to it. Lately it seems to go up and down in temperature, mainly when stopped. I usually can park and idle for quite a long time and the temp stays perfectly even. I'm wondering if I may need a recharge of the refrigerant. I've never had to do anything a/c related on a car and don't know if this symptom sounds like I'm on the right track.

Thanks in advance.

BTW, 2002 F350 Powerstroke with 170,000 miles

 

Go to the HVAC section and read the FAQs for starters. That will give you some background.

My 01 that I bought in February was exhibiting similar symptoms once it got really hot. When I checked the charge with my gauges, I found the compressor was weak. It got a new compressor, accumulator, and orifice tube on Friday and is now a constant 48 degrees at the center vent. Last weekend, the best it could do was 64 at speed and it would rise to almost 68 at stoplights. Needless to say, the wife wasn't a happy boater on that trip to and from the lake.

 

Thanks for the link. Guess I should scroll down further more often! Looks like I need to start testing a few things.

My wife's Subaru from new would cycle warm cold, warm cold and it drove me nuts. The dealer said it was designed to do that and it was perfectly normal. Needless to say, we didn't buy another Subaru after the lease was up.

 

Having a similar issue with my 02 350. Air will be blowing out but cold then especially in highway traffic @70-75mph suddenly feel like someone turned the heater on. The really odd thing is if I dial up the bulley dog, it will usually go back cold. But, not for long. Or it seems if I can bring the boost up for a few mins goes cooler too! Have a new condenser and a/c system pressures are on the normal range. I am at a loss for the cause!! Any suggestions??

 

If your refrigerant charge is correct and the compressor is operating normally, there's nothing wrong under the hood. Look in the dash.

If your outlet temp goes ABOVE ambient (as in HOT), you likely a problem with the temperature blend door.

 

As SHO said, IF "the compressor is operating normally"....

Mine was doing just as you describe. I did this:
SpringerPop's Compressor Clutch Air Gap

It's the easiest to check, and a quick fix if that's what it is.

Pop