Coleman Presidential II, M/N 3115A751: Blower will not stop

[pet575]

S/N: 017771369 (I believe a January 1977 model?)

Blower runs anytime breaker is on. Only way to stop blower is to turn off breaker. I replaced the 2 wire t-stat and no change. This unit has AC as well, and it does exactly the same thing whether heat or AC are chosen (which you select on the unit-not on the thermostat).

This unit is 100+ miles away, so I won't be able to get back to it until another weekend or so from now. I'm thinking the next step is the fan relay? In reading similar posts, you indicated this plan of attack:

"Turn t-stat OFF and with unit running continuously, follow these steps:

1. Set meter to test for 300+ vac and test these at blower relay:
Test across terminals 2 and 4= ???
5 and 6 = ???

2. Then set meter to test for 30+ vac and test here:
Blower Relay 1 and 3, test across those also.

3. THEN, go to Sequencer and leave meter to test for 30+vac and test across H1 and H2. Set meter back to test for 300+vac and test across M1 and M2."


Do you recommend the same plan of attack for this unit?
If so, I'm confused about Step 2. Set meter to test for 30+vac and test what? Just Blower Relay 1 and 3, but not across 2-4 and 5-6? I'm a little confused on that, but I think you said to "Test 1-3 at 30+, and then test 2-4 and 5-6 at 300+." Please confirm.

Also, will I be able to I.D. the numbers on the terminals (1, 2, 3, and 4) for testing, or is there some universal way of counting them (like top to bottom first, then left to right?)???

I would greatly appreciate your help.

Thanks!

[Robert]

1 and 3 = 24vac, set meter for 30

5 and 6 = 240vac, set meter for 300

2 and 4 = 240vac, set meter for 300



Yes, they are numbered. 1 and 3 at one end a little seperate from other four.


Then, 5 and 6 in middle and 2 and 4 at other end or top.




You should also test 4 to ground for 120vac.


Also, 6 to ground for 120vac.



You also turn power OFF at breaker, mark where each goes and remove wires from 5 and 6 and 2 and 4.


Then ohm across 5 and 6 and 2 and 4 to see if either set is closed and showing continuity.



Thanks for inquiring,
Robert

[pet575]

I will test it as soon as I can. Thanks for the input-greatly appreciated!!

[Robert]

The bottom ohms testing will avoid any live voltage testing if that is more comfortable .


One or the others should tell the tale.



Take care and best wishes,
Robert

[pet575]

Looks like I've put the cart before the horse on this one. I haven't been able to get back to test yet, but I got to thinking that I'm not even 100% sure what the sequencer and the blower relay *look* like.

I have a rectangular box with 2 switches on it. One says "Heat" and "Cool" (a 2 position rocker switch) and the other says "On" "Auto." Is THIS the sequencer?

Where would the blower relay be in relation to the sequencer? Would it be in between the sequencer and the blower itself when tracing wires? Or is it entirely separate?

Thanks again.

[Robert]

Hi,

Go here:

http://www.mobilehomerepair.com/ColemanElec.html


Sequencer # 3115-3571


Fan Relay # 3110-3301


For safety, with your lack of experience with these, the ohms test would probably be best and is just as good.


When it does this in heat mode, test at relay terminal 5 to ground for 120VAC.

IF you read 0vac, then problem is most likely the relay.


Is air coming from registers when it does this cool or warm in either mode ?


Thanks,
Robert

[pet575]

Yes. If heat is on then warm air flows all the time. If "cool" is selected then the unit outside will start and cool air flows all the time. Everything else is working normally, other than the blower never shutting off when the breaker is on.

Thanks again!

[Robert]

In a/c mode, when temp is satisfied, does the outside condensing unit shut off and blower only keeps running ?


Could be a 2 part problem possibly.


Thanks,
Robert

[pet575]

No. In A/C mode, they both run constantly. In heat mode, just the unit inside runs constantly. That's why I started with the thermostat. Plus, I wanted a programmable one v. the old-school lever model that was in it.

[Robert]

Then it's not a sequencer or relay problem. You may have a short for that to happen.

May need to trace check all wiring in low voltage circuit.

Due to that, might be time for a Tech to be called.


You have two different modes doing that and they are not related with each other in control wiring to do that.


Either a short or a miswire somewhere.


Thanks,
Robert

[pet575]

Interesting. Well, I guess I'll verify that the system really is doing what I say it is before I take any further action. Maybe I'm remembering incorrectly, so I'll rule that out first.

Again, thanks for the help.

[Robert]

I will add that IF in a/c mode, your outside condensing unit shuts off when it should, leaving ONLY blower motor running, then do the tests.

You are saying it goes into heat mode and heats fine and goes into cool mode and cools fine, but it nevers shuts off in those modes.


IF it is just the blower motor and even elements inside furnace continously running, do the tests.


However, IF outside condensing unit keeps running also in cool mode, may be a short OR a two part problem.


At condensing unit, remove panel at electrical controls area and look at contactor (large compnonet with wires at top, bottom and one small wire at each side).

In center is a bar across it, see if the bar is pulled in IF condensing unit is running continously.



Thanks,
Robert

[pet575]

Well, I got a chance to get down to test it last weekend. Before I even got a chance to do so, 2 things happened:

1. It was hot and humid, so I turned on the AC. It wouldn't cool the place overnight Friday night. Suspecting a low refrigerant level, I called out a tech who put 2.5 pounds in on Saturday morning. He also replaced some electrical connections outside on the condensing unit. Cool air flowing, so he left.

2. After the AC matter was dealt with, I discovered that my voltimeter had shot craps on me. No testing.

As the day warmed on Saturday, the AC ran continuously because of the issue with the blower not shutting off. Unfortunately, only *cool* air was coming out of the registers rather than *cold* air. So, the house never cooled off. When the tech was out, the temperature was low 70's outside and inside the house in the morning. This fooled us into thinking the R-22 was the answer since we got cool air from the vents. By the time the outside temp reached 90 late in the day on Saturday, it was up to 85 in the house. However, if you felt the line going into the house from the condensing unit, it felt cold like a bottle of beer in the fridge.

So, here is what I DID learn over the weekend.
1. My voltimeter doesn't work.
2. Both Heat and Cool mode make the blower continue to run (no change there).
3. My AC air is not cold enough to cool the house even if it runs all day.
4. Having a tech come to your house on Memorial Day Weekend is not cheap.
5. Tell the tech EVERYTHING when he comes (more on this below).

After all of this, I called the tech back this morning to discuss where to go from here. We discussed the cooling problems and then I told him about the blower problem I'm having (I hadn't told him about that because I didn't think it was related-DUH). I asked whether he thought the system would require a little bit more R-22 to make things cool.

His thought was that, given the other problems I'm having, the sequencer was most definitely bad. His quote, "I'd bet your lunch on that sequencer being bad." His thought was that the AC was probably working perfectly fine after the R-22 charge, but that the bad sequencer was causing the unit to both heat and cool the air at the same time-making the cool air not as cool as it should have been.

I'll buy his theory, but I DO have one question: would a bad sequencer cause the heating elements to operate even if I have switched the unit from "Heat" to "Cool" on the furnace?

What are your thoughts on the tech's theory? If you agree with him, I'll be purchasing a sequencer from you.

Thanks again for all your help.

[Robert]

Hi,

Yes, that could cause that and the tests would reval it. IF the first set of contacts welded shut, the element and blower would run non stop in heat and cool modes.


SO, blower would run always and the element would warm cold air as it passed over elements and thus be warmer air entering home.



Did he go look and verify his thought #1 ?


Did he find the leak before adding refrigerant #2 ?


He should have ran the unit through a few complete cycles before leaving and checked all relevant components.


IF he had, he would have found that problem easily.


Second trip should have been a freebie.


What is furnace model number ?



What was throwing me a curve w/o being there is when you said outside unit kept running too, yet you said it was cooling fine.


Actually, it wasn't cooling fine, air was warmer than it should have been and that is why it kept running outside because unit never satisfied t-stat.


The added info in your post painted the same portrait for me as I read it that it did for him as he heard it.


However, since he was there, he shouldn't have needed you to tell him that to find it it with a thorough service inspection.




Thanks,
Robert

[pet575]

Well, unfortunately I have to accept some of the blame for the tricky diagnosis here. This is my lake cottage in the middle of rural Missouri, and I've learned over time that some of the service people in this area don't like it if they find out you're trying to save yourself a little cash by doing things yourself. Due to some of the jerry-rigging that goes on locally, they won't even touch your stuff if they find out you're working on it yourself. The other difficulty I have is that a lot of guys don't work weekends down there and I live 2 hours away, so it is VERY difficult to get someone to come out on a weekend and equally difficult for me to get down there during the week due to my work schedule.

I had been poking around trying to fix the ongoing blower issue when the hot weather hit, so it wasn't something I shared with him when he got there. I thought it was a little strange that he didn't even come in to look at the furnace or anything and just went straight to the condenser outside, but at the same time was kind of glad because it helped avoid the "do-it-yourself" issue. So, it is my fault for not giving him all the info and his fault for not going inside, I guess. I don't feel right asking him to make a free visit.

The AC issue was throwing me as well, because all of my testing was done in 50-60 degree weather when I determined that the AC was blowing the proper temperature air. As I've learned before, and recalled now, the weather has to be at least 70-75 degrees before you can tell whether the AC is really putting out cold enough air.

So, to answer your questions.

#1. No, he did not verify the sequencer problem. We discussed if over the phone, and I have no way to physically give him access to the place.
#2. He DID pressure test the system prior to adding R-22, and showed me the gauge showing a reading indicating that stable pressure existed in the system. He concluded on the spot that, if I had a leak at all, it was tiny. To my knowledge, this 1977 unit had never been serviced for low coolant.

#3. Furnace model number is 3115A751.

Not sure why a service inspection wasn't performed, other than his mentioning to me that it was a holiday weekend and that he had several calls-I was his first. He was friendly and seemed knowledgeable, so I didn't press him on any inspection. I'm not ready to say yet that he is not knowledgeable, due to my failure to disclose, but I will certainly keep an the next guy to come out and make sure he does the inspection regardless.