Automotive Air Conditioning Information Forum

2008 Mazda 3 2.3L

Replaced old A/C Compressor and dryer due to the old compressor pulling a higher load than normal when engaged. Took the car for a test drive and got about 55F from the vents on a 95F day. Now a few days later the system doesn't seem to be blowing cold like it should, the vents now read 73F on a 90F day. Checked the pressure and they seemed slightly overcharged, released some pressure and no change to the temperature. There was about a 10psi fluctuation in the pressure before releasing the pressure but that has gone away. Static pressure with the car off is 104psi at 90F. At 1500 rpm the low is 27psi and the high is 225psi. The return line is also not as cold as before.

Before:
55F from vent on 95F day
Slight overcharge
Fluctuation of 10psi without the A/C cycling

After:
73F on a 90F day
Static Pressure is correct according the static pressure charge found on another forum
No pressure fluctuation
Low: 27 psi
High: 225 psi

I'm just trying to find out what the issue might be. The compressor and dryer are brand new and seem to be working fine but the system isn't working like it should. Any help is appreciated and if any more information is needed I can try and get it for you.

Mazda3_RX7 wrote:2008 Mazda 3 2.3L
Replaced old A/C Compressor and dryer due to the old compressor pulling a higher load than normal when engaged.

What does "pulling a higher load than normal when engaged" mean ?

Mazda3_RX7 wrote:90F. At 1500 rpm the low is 27psi and the high is 225psi.

Check your electric cooling fans, exterior cleanliness of the condenser. Maybe have a shop add the correct amount of refrigerant by weight, as your high pressure seems a little low.

For pulling a higher load than normal. With the old compressor it would cause a high drop on engine RPMs when engaged, making abnormal noise, and was showing the signs of a failing compressor.

Condenser is about a year old on the car and clean, have had to do previous work on the A/C before where I replaced the condenser, High & Low lines, and the evaporator.

I think your vehicle has a hot-water valve. If so, have you checked it to ensure that it's fully closing and not introducing any unwanted heat into the system? You can do that fairly easily by pinching off the hoses with padded locking pliers before and after the valve.