A/C not working properly

TMG6686

MEMBER
2011 HONDA CIVIC
4 CYL
2WD
AUTOMATIC
175,000 MILES

A/C comes on and stays on days that are below 88 degrees and no traffic. As soon as we get in traffic the A/C blows hot air. When we get back to cruising speed the A/C blows cold again. This is an on going issue with the car and it has been in two different shops where the problem can not be duplicated. The Freon was low due to a leaking condenser. That part has been replaced and the Freon recharged. No leaks. Still has problem. Both radiator cooling fans are operating properly.

Saturday, June 8th, 2019 AT 5:47 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Hi TMG6686,

This sounds like it has low Freon or a fan issue. I know you said they both have been addressed but you said that neither shop duplicated the issue so I question if they thoroughly checked the system.

When AC blows cool at speed but at idle it doesn't basically you are replacing the air flow that the fan is supposed to be doing by driving fast. You need air flow over the condenser in order to get the AC to cool. Without this it will blow warm.

Let's start with getting the pressure of the AC system on the high and low side. The reason is, the PCM will not turn the fan on when it is needed if the pressure is low. Refer to the attachment and let me know what you find.

If you don't have a gauge set, you can rent them from most parts stores. If you can get the pressures with the AC off and with it running. Then note what the ambient temperature is and we will be able to figure out which way to go.

Image (Click to make bigger)