No Heat from Coleman 3400-815

[slim463]

Hello,
I have a Coleman 3400-815 unit. Well here in the last few days it stopped blowing heat. The unit runs great, the fan blows great. just no heat. I took the service panel off and checked all the connections and fuses. Fuses tested fine. But, I wiggled one of the connectors going to a limiter. The connector on the limiter itself fell off. Well obviously the limiter is bad. The part number stamped on it is 3400-315. I see you have it. I am going to order. But, do I need to go along and replace the other 2, since it is a 1985 model. and they are not too expensive. Could this limiter cause my no heat problem completely? Will replacing it solve my heater failure? It can't be that easy? Right?
Any other ideas? Or guesses?
Also what is the limiter's function?

Thanks,
Slim463

[Robert]

Hi,

Yes, best to replace all at same time. The limit shuts down elements if they overheat the chamber.

Yes, it could be just that or may be a combo of more.


You can splice in that wire to complete circuit and bypass the limit JUST to see if all works ok.

If so, that is the problem.



Thanks,
Robert

[DavidW]

Thanks for starting a Coleman 3400-815 thread.

I have a puzzler:

Heating elements work fine. Blower motor works fine, but only in manual mode.

When it's in AUTO, the thermostat turns on the elements, but the blower motor doesn't come on. Then the limit switches cut the elements off for a minute or two, then the elements come on and then off, etc. Blower motor does not come on.

Sometimes it works fine for several heating cycles. Then the blower stops automatically starting.

I replaced the sequencers and still the same thing.

The Manual/Auto switch checks out okay with an OHM meter.

Any suggestions?

[Robert]

Hi David,

Can you start a new thread with your questions. We try to keep one inquirer and problem per thread. This keeps down confusion and helps make sure eveyone gets answered.


I'll check it out at that time later this evening.


Thanks,
Robert

[slim463]

Robert,
I bypassed the limiter as you requested, just to test. I turned the unit on and waited. The fan started. 30-60 seconds later a click sounded. The air did get warmer but, just not hot. I remember the air before this problem. The air was allot warmer. Or should I say plain hot. I remember the vents would get very warm to the touch. Now they just get warm.

I order the 3 limiters today. Maybe it could be another limiter?
I been reading allot of articles in this forum. Several state test voltage from here to here. But, I have no clue to which points on the what areas to test. I do have a multimeter, but am not the brightest with it.
I would love to test points, but will require much help with it.
Any suggestions? Any help will be appreciated.
The model number on the heat coil unit itself is:

Coleman No. 3400-335
240VAC-62.5 AMPS-15,000KW
16 & 17 GA C WIRE


Also I want to mention, when I bypass the limiter I removed it completely. I am able to look into the hole where the limiter was connected. The coils do glow reddish orange. But the limiter is located on the bottom. so I can only see the bottom set. I assume there are 3 coils, based on the position of the other two limiters. One on the bottom and one in the middle and one on the top. I clearly see the bottom one glowing.

slim463

[slim463]

UPDATE!!

I decided to bypass ALL the limiters. I removed them so I could see all the coils. Well the bypass worked! I see all 3 coils now glowing orange red!
Apparently all 3 limiters where bad. I am glad I ordered 3.
The air now blows HOT! Just like before.

I will keep you updated when the new limiters come in and installed. But more than likely everything well be back to normal.
Thanks for all your advise and wisdom!
Slim463

[Robert]

Hi,

That's great. Keep an eye on them when first installed, with the one falling apart, probably just weakened limits. However, they do open for safety also, so want to be sure that it isn't that.


With new limits, they should kick open quick if there is any problem with furnace.



You're very welcome, happy to help.



Thanks,
Robert