AC on the brink

[TimH]

The outside condenser fan motor went out two years ago. It was a 1/8 HP and I replaced it with a 1/10 HP motor that was available at the time. I since bought an exact copy of the 1/8 HP motor figuring it would be more efficient in the heat of summer. I planned on installing it in the next few days but tonight I noticed the compressor making a weird howling/hissing noise like it was giving up the freon ghost. It really freaked out the cat which is a twist since it's the cat that does the howling 'round here. After confirming that I was still getting cool air out of the ducts I went outside to check it out. The old 1/10 HP fan is running smoothly and the compressor seems to run okay but every so often it makes a crackling noise. No sign of freon leakage but an ominous hot electrical smell was observed. I'm wondering if the run/start cap is in the process of self destruction. There also seems to be an abundance of condensation moisture on and around the compressor and return coolant lines. I shut it down and plan to test the cap in the morning before running it anymore. Any suggestions or advice would be much appreciated. I am well versed in electrical design but do not have the equipment to recharge the freon if a compressor replacement is warranted.

TIA, Tim

[TimH]

It's pretty old. Maybe 20+ yrs. There doesn't seem to be a cap that's accessible and the wires going into the unit are dark and toasty. Now the compressor is no longer compressing. I guess it's time to call a service guy.

[Dr. Hardcrab]

The electrical smell COULD be the capacitor, but it may be the wires about to burn off of the terminals on the compressor. How old is the unit?

[udarrell]

If that unit is 20 plus years old, I wouldn't spend a lot of money on a system that old. A cheap fix; okay.

I would get a heatload done on your home for sizing and get bids on replacing the condenser and evaporator. Demand a scroll compressor and TXV refrigerant control on the evaporator.

I would also have the ductwork system checked for leaks and proper sizing.

If it is beyond your budget then forget it.

Use your own judgment! - udarrell

[Dr. Hardcrab]

I know people get in a hurry when they are without A/C, but if the unit is DOA, get at least three different companies to give you a price (a QUOTE not an "estimate"). Ask your friends and neighbors who they would use. Remember: The installer is more important than the brand name....

[Tim H]

My girlfriend owns the house and she is set on a whole new system as money is not really an issue. I agree that it's not worth spending the money on such an old system. And changing the fan motor was cheap and easy for me but the compressor is beyond my abilities.

How will a heatload test tell me how big to size the system and what numbers should I be looking for? The house is about 2600 ft2 including the basement.

Besides a scroll compressor what are the other types and how is the scroll better?

What does a TVX control do?

I'm also thinking about adding an electronic air cleaner. Does anyone have advice on this and know about what it should cost?

Thanks,

Tim H

[PipeDown]

The noise was probably the bearing on the compressor starting to go. Once it froze up(pun) the current to the compressor would have shot sky high (start up current - only it is sustained instead of momentary). Eventually the high current would cause significant heating in the wires and the compressor windings until either a fuse blows or the thermal breaker on the compressor opens up and shuts it off.

Either way as you already know, it is dead and not worth repairing. time to get a new one. Hopefully the cold coils in your ductwork are in good shape and can be reused.

[Stormin Mormon]

My girlfriend owns the house and she is set on a whole new system as money is not really an issue. I agree that it's not worth spending the money on such an old system. And changing the fan motor was cheap and easy for me but the compressor is beyond my abilities. CY: Please get three estimates from different companies. The guys I've talked to like some brands, but not others. The cheapest bid will likely be poor quality equipment, or installation.

How will a heatload test tell me how big to size the system and what numbers should I be looking for? The house is about 2600 ft2 including the basement. CY: Others are more qualified than I, to describe this. However, the tech should measure the house, consider the types of walls, and your location (lattitude, climate, etc). S/he will end up with a figure of about how much cooling power you need.

Besides a scroll compressor what are the other types and how is the scroll better? CY: The other types are piston, and rotary. The scroll is quieter, and uses less electricity.

What does a TVX control do? CY: A TXV stands for Thermostatic Expansion Valve. It is a valve that reguates the ammount of freon going into the evaporator. Depending on the heat load, an AC might need more or less freon to keep the coil cold. And, so it adjusts the freon flow. This maintains a good cold temperature, and is less likely to freeze the coil. It also reduces your electric bill. A coil without a TXV uses capillary tubes or an orifice. Some folks call an orifice a "piston" though I don't know why. Somehow, a hole that regulates the flow of refrigerant isn't a piston in my mind.

I'm also thinking about adding an electronic air cleaner. Does anyone have advice on this and know about what it should cost? CY: Don't think I've ever installed one. Worked on one years ago, but don't know what it costed.

Thanks,

Tim H CY: You're welcome.

[Stormin Mormon]

I'd agree with that. That, and the toasty wires.

That's a bad combination.