HVAC problem determination help needed

[no2gates]

Alright. Last night was uncomfortable without A/C but thankfully, temps dropped into the low 70s. I started the A/C back up at 8am, and it was running fine all morning, naturally

I called an HVAC outfit here at 8am and the technician showed at noon. He checked things out - drain line was clear, coolant level is good, and the capacitor is fine.

The only thing he found was that the fan motor was drawing 103 amps (max rating is 95, normal is about 75). He suspects that it's overheating and shutting down. He could not state authoritatively that replacing the fan motor would (about $1000 with labor and warranty) solve the issue, so I'll keep an eye on it and use it a bit more sparingly for now.

Thank you to everyone who offered suggestions!

The compressor might take 103 amps, but no way a fan is drawing that much power, unless it's got a direct short, in which case you'd have melted the insulator on those wires going to it.

 

[gasgas]

some of the outdoor units have a DC drive fan motor, they have a extra module on them to convert AC to DC , those are high $
Most trane and almost all units have at least a 5 year parts warranty, and IF you register a new unit with the MFG then you get a 10 year parts warranty
Post the serial number or PM me and I can check warranty on most units

 

[gasgas]

A fan motor should only pull .9to 3 amps max

 

[GeorgeS]

Alright, now you guys have me worried. The technician could not be sure it was a fan motor issue and he may have set or read his multi-meter incorrectly.

I checked and have the 10yr. extended warranty, so parts would be covered. I called Trane to see if the claim of 103 amp draw was possible, but the customer service rep could not answer, so she referred me to the local Trane dealer (Tiger Services near the airport).

Needless to say, the A/C has not cut out since yesterday so I'll wait to see if it happens again this week.]

Thanks to everyone who offered suggestions!

 

[TexasRedneck]

That's easy enough to answer....check the ampacity rating of the breaker servicing that unit....I've never seen a residential HVAC breaker THAT size. You didn't have a "technician" - you had an idiot that was given tools, no training - and told to go sell something. WAY too much of that crap going on right now.

 

[General Zod]

When I had that problem it turned out that the capacitor was completely stuffed full of thousands of electrocuted fire ants. You might double-check it, since it sounds like your repair guy was just angling to sell you an overpriced repair.

 

[Tamlibtoim]

Hey there just caught this thread…. HVAC tech here 20+ years experience. Not possible for your condenser fan to run at 103 amps. Could he have meant 1.03? Very possibly overheating if bearings wearing and unit over amping. The motor has a thermal protective device that “opens” when the motor gets too hot. If your fan was not running, can you tell if your compressor was still running? That is a major key to determine the problem. If compressor was still running and the fan was not then i would definitely be suspicious of fan motor failure. Since you have warranty check if it’s Parts only or parts & labor. Either way should be minimal cost to you. Hope this helps.

 

[GeorgeS]

The breaker is on a 35 amp circuit; the guy must have seen 1.03 as suggested and misread it (accidentally or intentionally).

He couldn't guarantee that replacing the fan motor would fix the problem, and I am glad I demurred

The A/C has been running fine since Tuesday, but if if happens again Trane gave me the name of their dealer here in SA.

 

[no2gates]

The breaker is on a 35 amp circuit; the guy must have seen 1.03 as suggested and misread it (accidentally or intentionally).

He couldn't guarantee that replacing the fan motor would fix the problem, and I am glad I demurred

The A/C has been running fine since Tuesday, but if if happens again Trane gave me the name of their dealer here in SA.

Damn decimal makes all the difference.

 

[GeorgeS]

Like with many things.

 

[Tnhawk]

The fan motor stopped running on my ac today. The compressor was running so I turned the fan blades and fan began running. Sound like a bad capacitor? I'm guessing this is the problem since it runs once the blade are moved.

 

[TexasRedneck]

Most likely.

 

[Grumps21]

I’ve used compressed air, followed by shop vac then finis he it off with vinegar through the line. This was about 5 years ago and no issues since. I don’t know if it was bacteria, algae or what, but what came out of the line was nasty. It looked just like oatmeal

 

[Tnhawk]

I ordered a capacitor from Amazon which is scheduled for delivery by 10PM today. Once the temperature reaches an uncomfortable level, I can start the fan by turning the blades. Fortunately, the compressor and contactor are good so this isn't an expensive repair.

 

[pronstar]

If you’re in a pinch, Grainger also sells caps and universal fan motors, at pretty good prices.

Ask me how I know…

 

[Tnhawk]

I used Grainer weekly during the years I worked for Sunoco. They could have the capacitor by next friday at over twice the price of amazon.

 

[Tnhawk]

New capacitor arrived a half hour ago and unit is blowing cold air again. Wife is happy to have it running today and I saved enough on repair to purchase another gun.

 

[pronstar]

I used Grainer weekly during the years I worked for Sunoco. They could have the capacitor by next friday at over twice the price of amazon.

My experience with Grainger is polar opposite compared with to yours.
Caps are $10-15 everywhere.
They had what I needed in stock.

When the blower motor failed, Grainger had it in stock for $5 more than having Amazon ship it. I didn’t feel particularly ripped-off, but that’s me.

I don’t use them all the time, usually when I’m in a pinch…sometimes they come thru with a great price and in stock, sometimes they don’t. But I think it pays to shop around.

 

[Tnhawk]

It seemed the Grainger locations I used in Nashville, Knoxville Atlanta and Chicago frequently didn't have the items I would need on the shelf but could deliver them in 2-3 days. I wasn't concerned about price as much as getting a part when I needed it. Most of their employees were good to work with however.

Sunoco and the fuel terminals I serviced usually required exact replacements or it would require approvals to substitute parts.

 

[GeorgeS]

A couple of weeks later, the AC is still running fine. With temperatures expected to reach 100 again this week, I am hoping we have no issues.