Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Slightly low low side and normal high side

dstevens on Mon September 15, 2014 7:43 PM User is offline

Year: 2005
Make: Lotus
Model: Elise
Engine Size: 2000
Refrigerant Type: r134a
Ambient Temp: 80
Pressure Low: 25
Pressure High: 220
Country of Origin: United States

The AC cools, but not as well as 5-6 years ago when it was charged. The condenser fan is not that great in the lotus, so the high side starts at 200 and climbs to 220. The low side is about 28 psi, but if you increase engine speed to 2000 rpm the low side drops to around 10 psi (high side stays at about 220 psi). Static pressure is 75 psi, and is the same as when charged.

Is the low side pressure dropping with rpm normal? If not, is the system slightly undercharged or is the expansion valve clogged?

Lotus AC systems don't cool that well to begin with (evaporator is small, cooling fans are small), so the operation may be normal.

Thanks for any help.

GM Tech on Mon September 15, 2014 8:25 PM User is offline

I always extract the refrigerant charge, weigh it, then start with the factory specified amount of refrigerant before I make any judgements about pressures- so until you have that done, anything goes and it is just a guess as to performance.

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.