Lennox AC Pressure question

[jeffer949]

So this is the first year in this house and while the AC is working and keeping the house cool it is only dropping the temp 11 deg and doesn't seem to be pulling moisture out of the air like we are used to in previous houses. So I check things out and throw some gauges on the system and find that the R22 is low. I have a friend who has his HVAC license so he can service his own rentals so I call him up and tell him to bring his R22 with him. This is where the question comes up. He was taught to never take the Low side above 75 psig. The Label on unit says it's designed pressure 144 on the low side and 278 on the high side.

It was at 55 psig when I started so I brought it up to 70 psig and said I would ask the experts before I take it up any higher. I feel like it needs more as im getting very little (is supercooling the right term?) like only 2-3 deg. It did bring my temp difference at the unit to 14 deg.

So should I leave it or should is it designed to have a higher PSIG and it needs more R22.

Thanks

 

[Milton Shaw]

That designed pressure is the max the coils and system can take, not the recommended charge. Normally on a R22 system low side should be in the 70 to 75 psi range. The super-cool should be from 5 to 10 if everything is working right. Check airflow on both coils to make sure everything is getting enough air across the coils. I have seen condenser units with the fan blade in the wrong place on the shaft and much lower air flow than it was designed for, also dirt on coil makes a lot of difference in cooling.

 

[jeffer949]

Thanks for the reply. I have cleaned the condenser coils. And I lubed the motor also but I didn't think to look at the fan position. Here is pictures of my A coil. Should I clean it and if so how with out removing it? Ive seen the aerosols but my wife is super sensitive to smells and im worried that it would set her off.

 

[kneeman]

Looks like that rusty thing has sprung a leak. Get a sniffer and check the bottom where the rust looks to be oily.

 

[justinjoyal]

Your friend has a license but can’t service your unit properly ?

Pressures, temps, amps, airflow... You need proper measurements for a proper diagnosis.