question for HVAC guys

[RedFish]

yep I saw post about the wiring.
Found the part at Amazon for a lot less too

 

[Oklacarcollecto]

What about this one? $14.99 with free shipping.

[ame="http://www.ebay.com/itm/Trane-RLY02807-Relay-Switch-HVAC-Replaces-RLY02257-Time-Delay-Replay-NEW-/131117614104?pt=LH_DefaultDomain_0&hash=item1e87380418"]Trane RLY02807 Relay Switch HVAC Replaces RLY02257 Time Delay Replay New 02807 | eBay[/ame]

 

[RedFish]

Thanks for that, already bought one though. 19 and change total, comes with a box ( as if that matters ).

 

[67Dart273]

I've pulled a few defective parts out of good boxes, LOL

 

[65cuda360]

:happy1:

 

[RedFish]

My interim plan was to set the fan switch to ON and then select heat. Fan running continuously couldn't harm anything but my power meter.
A chill in the air woke me about 4:AM . Relay had dropped out anyway. I smacked the side of the unit to get run and went back to bed. I moved the fan switch back to AUTO about an hour ago and its working fine.
I wont be surprised to find there is a fan motor problem involved. It is 24 years old.

 

[67Dart273]

Most blower motors are bushing bearings. I always pulled the blower, pulled it apart, and cleaned......many times actually hosed out........the blower cage and housing.

Then take an awl and punch small holes in the end caps so you can inject some (used to use either 20 or 30 wt non detergent) in one of those "Zoom" oilers.

Probably my worst service call of all time involved an empty summer home on the lake. It was a heavy winter, road was not plowed, and I had to chain up and slog through about a foot of snow just to get there. This was an aging heat pump and was being used to maintain minimum cabin temp, and had quit. It had not been serviced in years and years.

The heat pump was unfixable under those conditions, and should have been replaced. So I endeavored to service the electric furnace and set it up for "emergency heat". Pulled out the blower, and for some reason, there was a sort of hardware screen (factory) above the blower outlet. I took a look "up in there" to see how bad it was

Here were about 10 TAILS hanging down. Bunch of mice had gotten in there SOMEhow and died, and their tails were all hanging down into this screen.

My effin boss!!!!! I get back to the shop.............."Where you been?" "What tookyasolong?"

This was back in the day when we just had a "beeper" pager. So if I was somewhere without a phone, well, that's where I was!!!

 

[65cuda360]

If yer smacking the control box to get it to work, it's most likely a bad blower relay. Not many motors have oil caps, and you'd have to pull the blower wheel off to get to the one on the shaft end. The last few years they had oil plugs, they were yellow plastic. Have you checked to see if yer getting the heat elements on with no blower? Or are you getting nothing, no blower or heat elements. Does your test meter have microfarads? The switch would have MF or UF along with volts, amps, and ohms. If so, test your capacitor on the blower motor(unhook wires and discharge by grounding first). Most capacitors have the value stamped on them, it's most likely 12.5 -20 mf. If the capacitor is swollen or leaking, replace it, they are only $5-$10. Another capacitor test is to manually spin the blower wheel with the stat on, if it takes off, yer capacitor is bad. BTW, the reason you weren't getting a reading at the stat was there is no common if the stat only has 4 wires, you'd have to find common inside the AHU and meter it there.

 

[67Dart273]

the reason you weren't getting a reading at the stat was there is no common if the stat only has 4 wires, you'd have to find common inside the AHU and meter it there.

Well.........in older units there's normally enough load on the switched wires (white, yel, green) that you should be able to read from the red to one or more of those. That will at least tell you if you have transformer power, and that the unit has power. You must of course do this with blower off, heat and AC off

I chased my tail for awhile one time, a guy named "Richard" had added an extension to the stat wire AT THE TIME the house was built, and went from conventional 4 wire to a random chunk of 5 or six wire, wire nutted inside a wall.

I finally got wise, and found the entrance hole under the floor, and you could see the nuts UP in the hole. Would not have been so bad if he'd left 'em in the BASEMENT.

I was lucky..........there was no fire barrier in the wall from the floor to the stat, and I was able to pull a new stat wire.

 

[RedFish]

I cant access the heat elements at all without disconnecting the wiring and pulling the unit down and out. I would sooner have the whole unit replaced by professionals.
Thanks though

 

[65cuda360]

I cant access the heat elements at all without disconnecting the wiring and pulling the unit down and out. I would sooner have the whole unit replaced by professionals.
Thanks though

You can usually hear the sequencers click and the elements hum when they kick in. Some trane/American std. used a contactor instead of sequencers. It's just a heavy duty relay, they make a click when they pull in also. You could also put an amp clamp on one of the wires feeding the heater at the breaker in your service panel to see if it's pulling amps with no blower. Each element pulls about 15-20 amps when energized. Many times you'll have more than one breaker feeding your heater, so male sure all the power is off before you reach into the furnace controls.