98 5.0 A/C Pressures Question

[tresero]

I have been looking for a guide on what the pressures on the high and low side should be.

It is 104F in Las Vegas today, and I went to check since the air is coming out about 70F

The low side at idle was a constant 50 and the high side was a constant 350, that seems a little high, but with the high temps I wanted to see what it should be. This Explorer has almost 200k, only a/c replacement was the clutch.

Thanks

 

[safn1949]

Those pressures sound high to me,is your fan working? A lack of airflow will cause that..

 

[firepop5]

Pressures don't sound too high since outdoor temp is so high. Be sure your radiator and condeser are clean and fan shroud is in place.

 

[tresero]

I thought that since ambient temp was so high that the pressures should be higher than normal. The clutch never even cycles because of the heat.

I am sure the compressor is a little weak due to age, and that may be the difference. All the fans work, shroud, etc. The only thing that I haven't checked is the airflow, but I imagine it is ok. When the temp is below 100, the a/c works fine.

 

[scucci]

Rule of thumb- High side should be in the range of 2.2 to 2.5 times the ambient temperature measured at the condenser.

 

[ranger7ltr]

Pressures are way high even at 104 f...

Rule of thumb- High side should be in the range of 2.2 to 2.5 times the ambient temperature measured at the condenser.

The 2.2-2.5x ambient is standard for the high side...That being said 350 psi on the high side is a symptom of inefficient cooling...

Try this; spray the condenser with a garden hose and see how far down the high side pressure drops...It should drop to 200 psi or below... And the low side should drop into the 30's...And cooling should improve at the same time... And the compressor is working well if you are seeing 350 psi on the high side and 50 psi on the low side...

Sounds like it is time to backflush the fins in the radiator and condenser and perhaps replacing the fan clutch...Also when was the last time the cooling system was flushed and the coolant changed? Latent heat from the radiator will delay heat transfer from the condenser as well...Especially if the fan system is marginal...

And does the a/c vents drop while you drive or are they still staying high? Today it was 99 here in Austin and I was getting 38-40f a the center vent during the heat of the day...