Coleman evcon 3500A816 blower problem

[retiredusps]

Blower fan will not shut off. New fan switch, fan relay and thermostat installed. Thermostat reversing relay from you does not have the same numbered terminal positions as the old one so it was not changed out. What else could be allowing the fan circuit to stay closed

[Mark]

You may be having issues with the sequencer. Part number 3115-3571 for your unit. http://www.mobilehomerepair.com/ColemanElec.html

Mark

[retiredusps]

Thanks for the advice. Still have a ? or 2. Haven't done much digging into the unit. Where is the sequencer located? Is there a service manual/wiring diagram available? The fan runs all of the time--fan switch position( on/auto), system switch position (htr/AC) or thermostat setting have no effect in turning it off. I thought the sequencer had to do with heating only

[Robert]

Hi,

The sequencer controls the blower motor and heating elements in heating mode.

Did it first start doing this during summer a/c season or winter heating season ?

There is a blower relay that controls the blower for a/c use.

You can order parts & wiring diagrams here :

http://www.hvacmanuals.com/


Thanks,
Robert

[retiredusps]

Started during this AC season. Purchased fan switch, fan relay and thermostat reversing relay from your site. Installed switch and fan relay. Also a new thermostat purchased locally. The only thing that shuts the blower off is the main breaker. Tried several different switch and thermostat settings. The thermostat reversing relay I purchased from you has a different terminal numbering configuration than the old one and was not installed. Do you think a new sequencer will help???

[Robert]

Hi,

The sequencer is not involved during cooling mode. If changing the t-stat and blower relay did not help, you have a short somewhere in the wiring.

Is it JUST the inside furnace blower running continously OR is the outside a/c condensing unit running continously also ?

What thermostat reversing relay did you order ?



Take care and best wishes,
Robert

[retiredusps]

Robert,

It is just the furnace blower that stay running. The A/C unit cycles properly as does the heating side. The t-stat reversing relay was the 3311A

[Robert]

Hi,

T-Stat Reversing Relay 3311A is correct for your furnace with a 2 wire wall t-stat and 2 wire a/c control box.


With outside condensing unit cycling on/off correctly, reversing relay is fine.

The only components in circuit for blower motor during a/c is wall t-stat and fan relay.

Make sure both are wired correctly.

Then if still the same, check to ensure furnace switches on front of control box are set to COOL and AUTO.

IF your wall t-stat has mode and fan switches, set them to HEAT and AUTO.

That is proper settings for a/c use with 2 wire systems.

IF still no change, then time to trace circuit wires to find short causing continous current to motor.

Look closely at molex connector plugs and anywhere the wires enter the furnace through a hole that could rub the wires bare and enable them to touch.

If you list what wires connect to what terminal on current reversing relay, I'll walk you through changing it out with new one.


If you have a meter, test across fan relay 1 and 3 for 24VAC.

Also, test across 2 and 4 for 240VAC .

Then test 2 to ground for 120VAC and 4 to ground for 120VAC.


Be VERY careful there if testing, that is 240VAC LIVE voltage.

Only do tests if comfortable with doing so from experience.



Take care and best wishes,
Robert

[retiredusps]

Thanks for all of the info. Would like to be able to find a wiring schematic for this unit. Nothing available on the site you sent me a link to. It will probably be the weekend before I can get to my girlfriends' and do the tests. I will let you know the results as soon as I can. Thanks again for all of your help so far. Vern

[Robert]

Hi Vern,


You're very welcome, happy to help.

That link is the new page Mark has built for ordering those things. I haven't looked at it good yet, but the wiring diagram and parts diagram is available.

Call toll free tomorrow after 9 AM CST to 1-877-263-7860 and order it that way with Visa or Mastercard.

Or, have them send you a PayPal Invoice via email for payment with credit card.


That'll get you the wiring diagram quick.


Taake care and best wishes,
Robert