blower of suburban does not start when cranking up thermostat

[turfclubroad]

trying to get my suburban rt-30ma running (first time) but blower does not start when I crank up the thermostat (so I have not even started trying to fire it up...). Any suggestions?

thx

Wiebe

[Minno]

A quick check would be to bypass the thermostat temporarily to make sure it's not bad. If you connect the two thermostat wires together, and the fan still doesn't come on, then the fuse for the furnace would be the next logical thing to check. It runs on 12 VDC. You could use a voltmeter to check for power at the furnace as well.

Good luck.

Chris

[turfclubroad]

connected the wires of the thermostat, no luck. checked all fuses, all of them are okay. I checked the thermostat for current with a bulb but no effect: there should be a 12 volt current right?

My next step will be to check all wiring, if all the right connections were made. It seems as if some work has been done on the electrics and I am not sure if everything was reconnected 100%.

will report back later

Wiebe

[jump]

mine was and I had to replace the blower motor...

complete cleaning and system check...

[Minno]

There would be minimum current at the thermostat - probably not be enough to light a blub. It's in the milli-amp range. I would check to make sure you have 12 volts at the furnace, plus check the blower motor as Jump suggests.

[68 TWind]

I have an old NT-22 ( the crossover has been updated). I was having issues and really saved time trouble shooting by removing the unit from the case and working on it on my workbench. You will have good access to the blower wires, the sail switch, the limit thermostats and the relay. Any of which could cause your problem. You will need a 12v battery and some jumpers, but with it on the bench you can trouble shoot in in a just a few minutes. And it is a good idea to blow everything out with compressed air if it hasn't been pulled and cleaned in a few years. When you get the fan running, just rig up a propane line from one of your tanks and lighter her up.

Good luck.

[johnhumid]

The fuse for the furnace would be the next thing to check by a volt metter or some device that would be capable on checking some voltage....


_________________
Humidifier filters

[turfclubroad]

Well there is current in the blue wires (where the balck thermostate wites are attached to, but it does not get to the thermostat. However if I connec the blue wires (which should trigger the blower) still no blower.... I want to take the advice taking the whole unit out so that it will be easier to check everything, however I have no idea what the most efficient way is to dismantle. Its true that the furnace can be pulled out of the furnace mantle/box where all the duct attach to right? I have already disconnected the gas elbow, but what screws to unscrew to get the unit out (see attached pics) thx

Wiebe

[jump]

Starting with the screw outside at the vent, remove the entire vent cover by removing the four corner screws and the single screw in the middle of the top vent ... you know, in the middle of the "x"...I had to use some spray to get this one to release...it was pretty rusty...

then, inside ther is a screw at the bottom of the unit on the right...you can do this two ways: take the entire box out - in which case, you need to remove the other screw that is toward the front on the bottom right and disconnect all the hoses...but you should remove the innards of the unit without the outer box...and it should come out easier...its a tight squeeze either way and you'll wonder how it got in there to begin with...

there may also be a screw holding the furnace in on the bottom left but I did not have one there...

disconnect the gas line...be sure to turn it off first...

the electric connection is a plug with a squeeze fastener on one or both sides..

try that...I'll check back...pm me with your phone # & I'll give you a call if you run into any hitches or you have any questions...

but its mostly just unscrewing things...

also...what is that that is at the bottom outside the box? if that is a lip that sticks up at all, it should bee moved before the unit can come out of the box...

[turfclubroad]

okay, its out and the spark generator is working..... foud out the stupid way. I am sure there was no gas left in the furnace, but had sprayed wd 40 in to loosen the ctr outside screw...... Boom..... Like a loud exhaust pie of my tvr....

Anyway, so yes all the advice on how to get it out was spot on, I am now charging an old battery to start the diagnostics..... Not sure where to begin but I will work it out. Having said that, can anyone tell me if the fan should turn slow and difficult or very light, that is when turning with a finger? Right now it has more resistance than I would expect from an electric motor.

Will be back when the battery is charged.

Wiebe

[turfclubroad]

Got the battery charged and connected: first directly to the fan.... started..... smile on my face. Than I tried all connections. I essentially hooked up the unit to 12 v with the the thermostate wires connected. I thought I had it figured out that its the fan switch which was not working: if I bypass it the fan starts working. But I am not sure if I am making the right diagnostics as when I disconnect the thermostat wires the fan will also come on when I bypass the fan switch!!. What does the fan switch do: does that come on when activated by heat? HOw about the thermo relay: does that come on when the thermostate works by generating heat in the thermo relay?

thx

Wiebe

[jump]

if the blower motor is old and does not turn easily, then it probably needs to be replaced...be certain to replace gaskets and make sure that every thing fits flat where it should...don't put gas into the furnace on your bench until you have completely cleaned it out and made sure that everything is running properly. And did I say to clean it out and make sure that it is clean? While you are at it you might clean and test everything before you put gas in the chamber...oh yea...clean it real good, too.

There are reasons that there are signs on these things that tell us to take it to a qualified
technician.

[turfclubroad]

I have to say that I was shocked when it went kaboom when I pushed the electric ignitor, without any gas attached to it or having been it for years. I had not expected WD 40 to produce inflamatory gases.....

What else should be cleaned off before trying gas? In the end I am only going to replace the thermo relay as now I believe that that is the one which is faulty. (Read in my service manual that the fan switch only makes contact when hot.... mmmm mmm yes I know I am probably the last to find out).

Will report back when I have the parts fitted and tested...

Wiebe

[turfclubroad]

Sorted, everything works, its back in the trailer still needs a couple of screws to be fixed but otherwise happy as a clam. Still have to check if the thermostate is working, but bypassing it sets the blower to work and also the burner when the pilot is on...

So in the end it was the thermo relay...

thx for all the support!!

Wiebe