Automotive Air Conditioning Information Forum (Archives)

Gozzer on Fri July 19, 2013 1:00 AM

Year: 2000
Make: Mazda
Model: MPV
Engine Size: 2.5L
Refrigerant Type: R134
Ambient Temp: 95
Pressure Low: 40
Pressure High: 195
Country of Origin: Canada

My MPV has two evaporators, one in the front and one in the rear for the passengers. The larger line (in diameter) from the rear evaporator had a leak.
and was repaired, and the system evacuated and recharged.

We are having a heat wave this week. The A/C worked great in the morning when the ambient temperature was and 80 F / 70% humidity and in the evening when it was 85 F.

This afternoon reached 33 C / 91 F with 80% humidity. When driving around the city in stop and go traffic the A/C was cool but not cool enough to reduce the cabin temperature.
However when I got to the highway and maintained a speed of 60km/ 35mph the system worked very well.

Any ideas as to what can be contributing to the low performance at idle?

Thanks

Edited: Fri July 19, 2013 at 2:12 AM by Gozzer

HECAT on Fri July 19, 2013 1:27 PM

Poor air flow over the condenser. clean the dust, dirt, and bugs from the condenser-radiator air path. Verify or replace fan clutch; or verify it is kicking on the high speed of the electric fan(s). If you can put a gauge set on it, you can verify this is the problem by misting water on the condenser and seeing the high side pressure drop. This will verify poor heat rejection at the condenser.

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iceman2555 on Fri July 19, 2013 1:45 PM

It appears the system is undercharged. The indicated pressures are extremely low for the ambient temps stated. Have the system serviced, insure the correct charge..not by pressures but by weight. Could be a electric fan issue....but first would be to check charged rate.
Good luck,

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Gozzer on Fri July 19, 2013 6:15 PM

Great feedback.

Today was hot humid and very windy. Driving into the wind I noticed the performance improving. Over the weekend I will focus on the fan performance / condenser condition and take more pressure readings.

Thanks.