AC Gauge Questions

My AC isn't as cold as I think it should be. I looked at the videos by Timmah! and Chrisfix and here's what I came up with.

Temp with AC full blast and 1500 RPM.

Pressure with engine off.


Pressure with engine at idle around 750 RPM.


Pressure with engine at 1500 RPM.


Sight glass with AC off.


Sight glass with AC running.


I'm confused because I think my pressures are OK, but my sight glass and air temp indicate a problem. Other than take it to an AC expert, what do you think?

 

What is the ambient air temp? Just from the gauge readings it seems like a overcharged condition.

 

Watching

 

I don't know how long the engine was off before you took the "Pressure with engine off" picture, but shouldn't the pressure on the high side and low side eventually become equal? Just wondering if your gauges are accurate. Maybe it takes a while for things to warm up or cool down for the gauges to equalize.

 

Ambient air temp was about 90 degrees. The engine had only been off for a few minutes.

 

Your pressures are "OK" but I believe it's a bit low on refrigerant.

 

Here is a chart that is a good standard to go off of. According to your ambient temp and pressure readings you are probably slightly low on charge.

 

Dis-Charge the system, replace your dryer. Re-Charge. Thats about all you can do.

 

Ok. I charged my system and it's much colder.

My sight glass is clear where it showed bubbles before. But my gauges still read low on the low pressure side.

Idle with compressor engaged.


Idle with compressor off.


Approx 1500rpm with compressor engaged.

Ambient air temp was 93 degrees Fahrenheit. According to the chart I was expecting my low side pressures to be higher than registered. High side pressures look good according to the chart. Any ideas or suggestions?

 

Hi there,
When recharging your ac system did you base when to stop off the sight glass or the ac gauges? Thanks

 

I watched the gauges and the sight glass. The low pressure went up a little stayed around 30 when the compressor was engaged and at 1500rpm. Didn't seem to matter how much I added. I checked the sight glass a couple of times as well. I'm worried that my low pressure gauge might not be accurate. Not sure why else it would have stayed around 30.

 

Bump for suggestions.

 

What's the problem? You said it was much colder. Is it not working well enough? If there was more freon in the system your pressures would be higher, but it may not work any better.

 

I added what I think was around 16-18 ounces of freon to a system that should only hold 22 ounces fully charged. So I was thinking that the low pressure would be higher. But maybe I need to add a few more ounces. Afraid to overfill and cause problems when the system seems to be cooling well. Also don't want to cause problems if underfilled. Is one condition worse than the other?

 

It shouldn't cause a problem being slightly unfilled other than not cooling as much. If you are satisfied with how it works and cools now then I'd just let it be. I don't know about those temp/pressure charts. Seems like more of a guide rather than exact.

 

I didn't base it on the pressure at all. I based it on the window. Once that was clear and good to go. I then checked my gauges and noted where they were for future reference. This is actually what Timmy told me to do. It worked good for me. I just did this a few weeks ago.

 

What pressures did you have at what ambient temperature?

 

And is there a reference AC temperature range for a given ambient air temperature that the system should be producing at idle or 1500rpm?

 

Good job! I'll take a note. Can you describe exactly the reason for this operation of the air conditioner? Just wondering. Was the indoor unit filter clogged with dust? Did the fan winding of the indoor unit burn out? Was there no freon in the system? Or was there too much of it? Once my air conditioner didn't blow cold air at all, and I had to contact the service marvellous.sg. The guys did everything well, but I got the impression that I could fix it myself. That's why I want to find out everything now. Air conditioners often behave like this after winter, so I want to be ready for anything.

 

43f at 93f ambient is pretty damn good