Automotive Air Conditioning Information Forum

Lately it's been mid to high '90s. It reached a hundred the other day.

I did check my condenser fan. With my AC on, My condenser fan is on full speed.

Mind you that I just have the whole system rebuilt a year ago to the month.

Lately here I've noticed that when writing down the road everything's hunky-dory. As soon as I've been sitting in traffic for say like 5 minutes the temperature starts dropping. It's noticeable. I have a thermometer in one of my vents for this.

When it was idling I felt the skinny line and the fat line for the AC. The skinny line was hot but the touch the fat line wasn't cold at all. Maybe it's a little bit cold.

Is there any basic way to check to see what might be going on?


It could even be the temperature outside. I wonder if there's some kind of safety switch or thermal overload type deal that makes the AC going to underdrive when it gets really hot outside

1. please state make/model/year of car and how many miles on the clock
2. who rebuilt the system a year ago? You ? or ?
3. My first thought is to use a garden hose and mist the condenser (keep misting it) and check your vent temps and skinny/fat line temps and report back

Please provide the year, make, model, and engine size so that we can help diagnose this.

tbirdtbird wrote: ↑Wed Aug 09, 2023 12:34 pm
3. My first thought is to use a garden hose and mist the condenser (keep misting it) and check your vent temps and skinny/fat line temps and report back

I also agree with above. Seems like an issue of improper condensing, likely due to bad electric fan(s) or bad fan clutch or debris covering condenser.

Electric1 wrote: ↑Wed Aug 09, 2023 12:15 pm It could even be the temperature outside. I wonder if there's some kind of safety switch or thermal overload type deal that makes the AC going to underdrive when it gets really hot outside

Just the opposite would be the case. If your vehicle has a variable displacement compressor, the compressor would be pumping at full displacement and the condenser fan(s) would be roaring to overcome the heat load and to cool the cabin sufficiently.

Sitting in traffic vs driving down the road have two different variables.

1.) airflow across the condenser
2.) engine/compressor speed

If your fan is running at high speed and your cooling is not up to par, I'm inclined to believe that your charge is a little low. When you drive down the road, the engine and compressor are spinning at double the idle speed or more and can move more refrigerant volume.

I do agree that you need to check the condenser to see if it is clean.

Take the vehicle for a spin and get it all warmed up. Return to your shop/garage/work area, place a set of gauges on it, and record the pressures when it is not cooling. Idle ad 1500rpm

Please don't add refrigerant when you are not sure of the true nature of the problem. You might increase the issue even more.

Vehicle information is also helpful to answer questions correctly.