Author Topic: HVAC question (Read 2065 times)

RadioFreeSeaLab · « **on:** September 03, 2007, 04:54:18 PM »

My parents have a Trane Executive central air unit, and today it seems to have crapped out. The fan in the house turns on, and fan on the unit outside turns on, but the air is not cold. The outdoor unit, whatever it's called, seems quieter than before. The cooling fan turns, but there isn't the usually pump noise. I don't know anything about air conditioners, but am I right in assuming that the compressor has crapped out?

cassandra and sara's daddy · « **Reply #1 on:** September 03, 2007, 05:11:35 PM »

sounds like comp is not working but there are many things that can cause that besides compressor croaking

RadioFreeSeaLab · « **Reply #2 on:** September 03, 2007, 05:14:50 PM »

Such as?

Sindawe · « **Reply #3 on:** September 03, 2007, 06:22:27 PM »

Failed relay that supplies power the compressor. Even if the compressor works fine, it don't work with no power.

Failed controls that tell the compressor when to run and when to not run. AKA the AC is brain damaged.

Dirty cooling fins. AC works by taking the heat from the air in the house via a phase change material of liquid to gas (IIRC) and dumping the heat to the outside atmosphere as it condenses back to a liquid. If the phase change material can't dump the heat, it never cools off and condenses and can't pick up more heat from the house air.

Sounds like its time to call a professional.

cassandra and sara's daddy · « **Reply #4 on:** September 03, 2007, 06:48:44 PM »

mine crapped out once when a small snake shorted out the relay outside

280plus · « **Reply #5 on:** September 03, 2007, 09:05:00 PM »

Yes, it sounds like the compressor is not starting, best get a pro in there.

jeepmor · « **Reply #6 on:** September 03, 2007, 09:17:01 PM »

Look online for schematics or pull a couple panels first. Schematics are frequently just inside the service panels. It might just be a fuse has blown due to dirty coils. It's usually an easy look before calling the pros and sometimes there are extra fuses clipped in there too. Beyond that, it usually requires a pro because he can get the parts you need and has the experience.

Call an HVAC company that specifically deals with Trane for best results.

Thor · « **Reply #7 on:** September 03, 2007, 11:23:50 PM »

Sounds to me like it developed a freon/ whatever gas they use nowadays leak.

280plus · « **Reply #8 on:** September 04, 2007, 04:47:40 AM »

I've seen numerous examples of insects getting in between the contacts for the compressor. I've often wondered how that must have felt. shocked

Brad Johnson · « **Reply #9 on:** September 04, 2007, 06:33:31 AM »

Quote

I've often wondered how that must have felt.

I bet it was a smashing success.

Brad

Ron · « **Reply #10 on:** September 04, 2007, 07:36:12 AM »

Let us know what it is when you find out.

I'm betting burned wires at the compressor, bad capacitor or bad compressor.

Usually the outdoor condenser fan runs when the compressor contactor pulls in on a call for cooling. Seeing as the outdoor fan is running I suspect the contactor is functioning normal.

AmbulanceDriver · « **Reply #11 on:** September 04, 2007, 07:51:45 AM »

Quote from: Brad Johnson on September 04, 2007, 05:33:31 AM

Quote

I've often wondered how that must have felt.

I bet it was a smashing success.

Brad

And quite the shocking experience......

280plus · « **Reply #12 on:** September 04, 2007, 10:19:01 AM »

I know what goes through their minds though...

A little over 200 volts! laugh

Nick1911 · « **Reply #13 on:** September 05, 2007, 06:37:04 AM »

HVAC must be real hard. Considering the general DIY spirit of the forum, everyone seems mighty quick to default this one to the professionals.

I haven't worked on central air, so I don't know. I have worked on automotive A\C, which was very simple.

What makes HVAC hard?

K Frame · « **Reply #14 on:** September 05, 2007, 06:52:40 AM »

It's not particuarly hard, but it does take knowledge, skill, and TOOLS to diagnose/fix a modern heating/cooling system.

If you go mucking around, you can hurt or kill yourself, or worse, cause thousands of dollars of damage.

BrokenPaw · « **Reply #15 on:** September 05, 2007, 06:53:13 AM »

I don't know about everyone else, but my line in the sand for DIY is labeled "240 volts".

-BP

280plus · « **Reply #16 on:** September 05, 2007, 08:14:26 AM »

I'm a pro so I always defer to same. There are a number of reasons why his unit is not doing what it's supposed to. An experienced guy will go right to the correct answer while a DIYer could spend hours fiddling with it and either not fix it or make it worse. Plus that 240V lije in the sand is a pretty good parameter as well. We don't want Dave to fry now, we don't really have a recipe for fried Dave. shocked

K Frame · « **Reply #17 on:** September 05, 2007, 08:31:39 AM »

"An experienced guy will go right to the correct answer..."

BBBBBBBBBBWWWWWWWWWWWWWWWWWWHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAH!

Stop it, you're killing me!

laugh

ilbob · « **Reply #18 on:** September 05, 2007, 08:57:30 AM »

There is nothing that makes 240V inherently more dangerous than 120V. They are both very dangerous to amateurs.

HVAC systems tend to be fairly simple until you have to look at the refrigerant, then it can be more of a hassle just because of the tools you need, and the experience to understand what is going on.

Many A/C compressors have a manual reset switch that trips if the refrigerant pressure gets too high. This will often cause the compressor not to run, while allowing the fan to run. If this is your problem, you can try resetting the switch, but most likely it will just trip again. That would be a signal to bring in someone competent.

RadioFreeSeaLab · « **Reply #19 on:** September 05, 2007, 09:02:31 AM »

We looked, but couldn't find a switch, or a fuse inside the unit. I was only there to help troubleshoot, it's my parents' place. If they ever get around to fixing it, I'll let you all know what was wrong.

K Frame · « **Reply #20 on:** September 05, 2007, 09:05:36 AM »

The fuses are normally part of the main power block that should be mounted on the exterior wall of the home right next to the unit. Most have two big barrel fuses as part of a pull-out.

A simple resistance test will tell whether the fuses are shot or not.

If one or both are shot, don't simply replace them. There's a darned good reason why they blew.

RadioFreeSeaLab · « **Reply #21 on:** September 05, 2007, 09:07:10 AM »

That was the first thing I tested, they are working fine. The fan spins, but the compressor doesn't turn on. We were unable to find a reset switch or smaller fuse anywhere in the unit.

Brad Johnson · « **Reply #22 on:** September 05, 2007, 09:16:32 AM »

Quote

The fan spins, but the compressor doesn't turn on.

Contactor or relay. Some units use seperate circuits for the fan and compressor.

Brad

K Frame · « **Reply #23 on:** September 05, 2007, 09:23:00 AM »

"Some units use seperate circuits for the fan and compressor."

And Trane is one of them.

A few years ago my unit wasn't cooling. Fans were spinning, but compressor wasn't running.

Turns out the crankcase heater shorted out and popped the compressor side fuse. Fan was still getting power, but the compressor wasn't.

Guy put a new fuse in, pushed the block in, and it sounded like a .22 going off.

280plus · « **Reply #24 on:** September 05, 2007, 11:03:18 AM »

Quote from: Mike Irwin on September 05, 2007, 07:31:39 AM

"An experienced guy will go right to the correct answer..."

BBBBBBBBBBWWWWWWWWWWWWWWWWWWHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAH!

Stop it, you're killing me!

laugh

What? I did that today. grin

I looked at these units and within 60 seconds knew exactly what was wrong with them. Meanwhile some amatoo had been frigging around with them forever, correcting the symptoms, but not the problem.

News:

Author Topic: HVAC question (Read 2065 times)

cassandra and sara's daddy

cassandra and sara's daddy

Ron