I have a mixed system upstairs, At a time when I couldent afford much, I had a friend in the business who rigged my up a system to heat and cool my house. at the time I had a non functioning 2.5 ton heat pump with a locked compressor, and burned out heat coils, and it was the dead of winter.
He gave me a old Janitrol 2,5 ton air handler, and a 3.0 ton compressor, and we installed it one weekend, total cost was $900.
This system has functioned great for 3 years now...longer than I thought it would to be honest.
In the past 2 weeks the unit has frozen up about 4 times. Freon was checked, and the guy said it was fine, and didnt add any....so he said he would suggest cleaning the coils. I payed him to clean the coils, and the system worked fine for a day or two..and one morning...it was frozen again.
I have been fooling around with it since, and I have been able to keep it from freezing...and dont understand why.

1. It only freezes up at dusk or at night, it never freezes in the hotest part of the day, even if it runs for hours.
2. It only freezes up at settings below 73 degrees, if the unit is set to 73, its fine, if it is set to 72...it freezes.

anyone have any ideas what would cause such a issue?

I have almost enough money saved to put in a new Trane unit, but I still have about $1000 to go.
I am the kind of guy who sets his sights on something and dosnt stop till I get it, so even if this system fails, I am not prepared to settle for a cheaper unit now. I will probably continue to tinker with it till its replaced.

 

You dont say, is this still a heat pump? How about the bypass or check valve there ? If TXV is it ok. Sure the freon is clean ? Not contaminated
or no noncondensables Should have put a 2.5 ton high side on a 3 ton coil. Blower motor ok dont slow down?

ED

 

Make sure your condensor coils are clean then re-check the refrigerant charge. I've had many cases where tech said charge was good but unit wasn't cooling properly/freezing up. Cleaned the condensor and was able to add refrigerant. When dirty, the pressures will rise and the tech thinks it is ok.

Your system will be especially critical because you are already starting out with a 3ton banging up against a 2.5 ton coil.

 

Like I said, at the time I was in a bad place, middle of winter, no heat, and a wife and 2 kids..I was doing everything in my power to get something to get heat in the house.

I hadnt thought about dirty freon....we did use the old lineset, so dirty freon is a good possibilty, although I do remember him hooking up some kind of machine to the lineset, to flush it.

I have rechecked the "A" coil in the air handler, it seems pretty clean, but I washed it down again with bleachwater and a brush, a flashlight shines through it, so I am figuing its clean enough.
I did notice one thing...a build up of compacted dust on the blower scroll fan. I am assuming that this could reduce the fans ability to move air....thereby slowing the air across the coil..and leading to a possible freezup?

tonight after things cool off I plan to pull the blower and clean the scroll fan.
If I find a number on the Janitrol air handler, would anyone he able to tell me what speed the fan is running....maybe I could move to a higher setting?

 

The blower blades cup like. Make sure you get all the dirt out and out of all the blades. On most 3 speed blower the black is high.

ED

 

I went through the air handler, as best I could.
I washed down the condensing coil, and then used a wet dry vac with a brush attachment to comb and vacuum the fins on the “A” coil.
I then removed the blower, housing and all, disassembled the fan from the blower and cleaned the fan and housing with a hose outside.
I put it all back together, and buttoned her back up.
I did not notice a real increase in air flow, but I felt better anyway. That night …she froze up again. I was pissed….
I decided it was time to get a new system.
Still being the DIY kinda guy, I went up to measure the ductwork, as old as the house is, I had decided that if I needed a new unit, I would replace the ductwork also.
I went back up into the elevated hell known as my attic, and started measuring…
I followed my trunk line behind a skylight box….I felt a wisp of cool air….I looked down and to my dismay…a 90 degree joint was broke open…right at the seem.
To make a long story short, after I fixed this joint, and one other I found, the unit made it through the night without freezing…..
Could a leaky duct system cause a unit to freeze up…or did I just get lucky last night?
I am still planning to replace the ductwork, but that’s a whole other thread

 

I also found a trane, 3 ton air handler and I am wondering if I could possibly replace this old Janitrol 2.5 ton air handler with it.
The info label on my current air handler is not legable...but I am sure it is 2.5 ton.
My current compressor is a Goodman CPKE36-1A, I am pretty sure its a 3 ton compressor.
I have found a Trane TWE036C14FBO air handler, 3 years old, and in pretty good condition...excellect condition compared to my Janitrol.
I am curious if it would be worth swapping out the air handler...or just bite the bullet and buy new.
My basement unit is a 1.5 ton Comfortmaker, it has a scroll compressor and I am very pleased with its performance.
I am figuring the mixed system I have now is at best giving me a 8 seer rating, If I moved to a 2.5 ton 14 seer comfortmaker, I could stand to reduce me electric useage by a bunch.
Sorry...not meaning to bore anyone...just thinking outloud.