I've mated a 1991 Rheem Ahu with a 2001 Trane XL1800 Condensing Unit. He condensing unit is dual stage compressors and I have the high side wired to call. I know need to upgrade the ahu and the honeywell chronotherm III t-stat but budget is not allowing it yet. I had a new coil installed with a flat coil 3 years ago. The ahu is in the attic. During the hot part of the day (103 plus) the unit doesn't keep up. The inside temp will rise to 82 plus degrees and will not shut off until later in the evening (10ish). The condensing pressure read low 67ish and the high 210ish drawing about 12.5 amps on both feed leads. I checks the ahu coils and their clean. Any suggestions?

Thanks
Daniel

If everything is clean,, coils inside and outside,, the filter clean, you might be charged a little to high with freon
What does the tag say when running what the amps should be?

What was the outside temperature when the gauge said it was 210?

The tag only refers to max amps of 22.
The air temp when I'm having all the cooling issues is over 102.

Oh by the way thanks Wmproop and HVAC1000!!

210 is low for that outside temp. Looks like you might be low on refrigerant

Wouldn't this affect the low side pressures also. Also could there be some restriction in the line causing pressure loss? Don't know that's why I'm asking , Thursday the pressure was high pressure was around 235 and 104 outside. It seems to fluctuate some.

sounds to me like its time to have a certified tech come in... they can watch and monitor the system and find the exact problem. Would need to know superheat and subcool, temps, pressures, splits to know exactly what's wrong.
but it sounds more like low charge, but without all the variables it is hard to say.

Superheat and subcool temps? How would I go about attaining these? I have access to just about all the tools needed . I'm trying to learn something on my own, I have access to ac help of friend and family, but this one I wanted to fix on my own. I don't want to burn up those favors on something I can take care of on my own, its important that I exhaust all my potential first before askinf for there help. Thanks though, you all educating me is much appreciated.

Are you certified to handel refridgerant?
If not than I can not assist you any further. I do not need to take the chance on a fine or jailtime if for some reason you do not handle the refridgerant properly and something goes wrong.

Sorry.