My other Ford AC help

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

coolzzy

Full Access Members
Joined
Apr 16, 2018
Posts
374
Reaction score
166
Location
Idaho
So the AC in my 17 expedition is adequate, not what I'd call ice ice cold but it does the job, even more so now that I've tinted the front windows to 20%.

My other vehicle is a 12 focus, and I've asked this question in the focus forum but there didn't seem to be a wealth of knowledge or responses to AC questions over there like there is here. I'm just not sure how to interpret my high and low pressure readings

My AC will get bone chillingly cold when it is above 90 but is mediocre below that temp and seems to cycle between vent and AC when outside temp is below 90 as well, even when set on max AC setting. It uses a constant AC pump so you only hear it engage once when turned on and the compressor clutch remains engaged at all times (there's a name for this type of compressor but I don't recall off hand). Anyway, my low side pressure never goes above 32 and the high side pressure is 220 which seems to indicate proper fill. However I have added refrigerant when I bought the car and the AC got noticeable colder but with no change in pressures or cycle time.

If my compressor were going out, would it not be able to maintain the low side pressure high enough (I think for the 90-100 degree temps we've been having it should read 35-40 on the low side)? Wouldn't adding refrigerant always result in a higher low side pressure if the pump was working correctly?
 

stamp11127

Full Access Members
Joined
Mar 10, 2012
Posts
6,218
Reaction score
1,250
Location
Temple, Georgia
When compressors start going out you can have low pressures on both sides or high pressures on both sides. Your pressure readings are what I set my system at.

I would look into why the system switches between vent and max ac. Normal cause is a vacuum leak.

Adding refrigerant will raise both low and high side pressures but more noticeable on the low side. The high side will very more with the amount of airflow through the condenser. Reduced airflow equals higher pressure due to less condensing of the refrigerant and higher retained heat.
 
OP
OP
C

coolzzy

Full Access Members
Joined
Apr 16, 2018
Posts
374
Reaction score
166
Location
Idaho
The controls are electronic, no vacuum lines. The AC lights on the panel never turn off, the air just goes to cabin temp and smells humid, then after roughly 30 seconds it starts getting cold once more. I can feel the change in temp by resting my hand on the low side ac tube under the hood, it will alternate between cold and ice cold. I just don't get why when the outside temp is above 90 the AC is super duper cold. And why my low side pressure reads 30 whether it's 80 or 100 outside temp. I thought r134a increased pressure in relation to ambient air temps?
 

stamp11127

Full Access Members
Joined
Mar 10, 2012
Posts
6,218
Reaction score
1,250
Location
Temple, Georgia
You may want to get the Ford service manual off ebay to help diagnose the ac issue. If I remember correctly the compressor you mentioned could be a variable displacement type. If it is I would look at the control for the compressor.
 
Top