So my AC likes to not work when it is over 95+ F (hot days) outside, but works fine on warm days, so I am at a loss. I have resoldered the AC controller board and replaced the compressor relay per my readings on this forum. I decided to get a manifold gauge and the pressures don't make sense to me.

With the compressor off I recorded Low - 37 psi, High - 125 psi
At 1500 RPM Low - 92 psi, High - 175 psi

Could anyone make sense of this? I have read high low pressure could mean blockage.

 

I forgot to mention that it was around 85 degrees outside during the time of the readings.

 

What year?

How long had the A/C system been off when you measured the unequal pressures? If given more time, do the high and low side eventually equalize with the A/C off?

Here's how to troubleshoot when the low side pressure is too high:

 

Thanks for the reply. The car is a 93 with R134a retrofit that was done 2 years ago. Actually I'm not sure how long I waited. I will try again after work today since it has been setting for a couple of days.

 

After doing even more research online, I am beginning to think that the harbor freight instructions are wrong for the couplers on the manifold gage. I followed the instructions and used counter-clockwise to open for the readings, but like many people have hinted at on the site this is backwards? Is clockwise actually open?

Can someone confirm this that have the same gages?