Any hvac technicians?

[jmaglipay]

My ac/heating unit recently stopped working out of no where. The unit turns on but there no cold air and the blower fan does not turn on. I checked the fan and the condenser outside the house and the coils and they were frosted up.

A quick Google search told me to check my filters and to check for any leaks. All my filters are clean and i didn't see any leaks. I did a quick clean up on the coils and fins and the surrounding areas. I tried turning on the unit again and after 15 minutes it would shut off and the lines would freeze up again.

I finally went up to the furnace to see if anything else is wrong. I did notice that the blower would hum and not spin. I didn't see any leaks anywhere.

Anyone have any advice what else to check before I call a technician?
Thanks

[onthehunt]

If your unit is lying on its side. Motor bearing worn out allowing rotor to lower and not line up with stator causing it not to run. Take upper bearing parts and install on lower end to get running until you find a new motor.

[onthehunt]

I'm not a hvac tech. It's what happened to me on fourth of July weekend and momma needed air.

[FF90]

Possibly a bad capacitor on fan motor, be carefull as capacitors can be very dangerous. do more research on caps BEFORE trying any repairs, the good news is they are relatively inexpensive to replace and some parts houses have cap testors to check the old one

[draftingmonkey]

Could be a bad cap as FF90 stated. You stated that it is the fan in the furnace unit. I would pull the fan out and check to see if the motor spins/moves.

If it does spin freely by hand then probably the cap is bad and needs to be replaced.

If it moves with difficultly, lube the heck out of it at the oil points, usually at both ends of the motor there are lube ports. Unlubed or bad bearings can keep a good cap from having the power to kick start the motor. If you can get it to spin freely you might see if it will start at all. If not possibly a bad cap.

If it is frozen it would probably be faster to hire a tech to come in and replace the fan motor.

Every year before A/C season I yank the fan out of the furnace unit and use a compressor to blow all the dust out that I can and then I hit the lube points with light machine oil until the oil ports stay full.

There are a lot of videos on youtube on how to test furnace fan motors, caps and control boards for correct operation. Hope it is an easy to diagnose and fix issue.

[jmaglipay]

The capacitor is next thing I will check. The blower does spin freely by hand.

If the blower does not work, is it one of the factors that will cause the lines to freeze up? Is there any way to check refrigerant levels?

[draftingmonkey]

The capacitor is next thing I will check. The blower does spin freely by hand.

If the blower does not work, is it one of the factors that will cause the lines to freeze up? Is there any way to check refrigerant levels?

Yes it can. If you read this list you will see that if the air inside is not flowing across the evaporator coils it can cause the outside condenser coils to freeze up.

BEWARE about checking the refrigerant on an older A/C unit. Every time the charge is checked you lose a little refrigerant. My 30 year old Carrier uses R-12 which is banned and can not be recharged. I will run it until it no longer works or the Trane furnace gives out.

[onthehunt]

Yes. I bought the capacitor first. Cheep item to buy and try first. But they don't put real bearings in these motors and won't support the weight of the blower fan while laying on its side.

[pacrat]

Yes. I bought the capacitor first. Cheep item to buy and try first. But they don't put real bearings in these motors and won't support the weight of the blower fan while laying on its side.

Not a practicing tech but went to school long ago for HVAC. As others said, No "A coil" fan running, will cause your trouble with freezing coils. Because NO thermal transfer is happening in the coils without the fan. This causes internal pressure to spike and the unit will shut down on High limit switch. To protect the compressor.

This below is intended for future motor woes.

Inexpensive fan motors do not have as you said "real bearings". They have "porous bronze bushings". Called "OilLite Bushings". If repeated allowed to run dry. The pores on the internal surface "gum up" and then friction causes them to "glaze" which seals the pores and restricts the oil from reaching the bushing/shaft juncture for lube. Relubing with fresh oil and rapid repeated spinning will often free them up and allow the shaft to spin as intended.

That's why it is important to properly lube service those often neglected motors.

Hopefully your main issue is the start cap easy fix.


JM2c

[jmaglipay]

Thanks for the advice Calguns. Hopefully it's the cap and I thing else.

[jon94520]

Make sure power is turned off at the circuit breaker, not just the on/off switch. Ive seen 220v units that only eliminate one leg of voltage. Also before touching the capacitor leads with your hand drag an insulated metal screwdriver across both leads at the same time to bleed out any possible voltage in capacitor. Ive seen those capacitors shock the hell out of techs.