# Comfortmaker RPJ-II



## Homer-Cristian (Feb 28, 2009)

High limit is tripping. Cleaned filter and evaporator coil. I have all registers open. The high limit was touching the heat exchanger. I bought some sheet metal and made a gasket so that the HL woul not touch the heat exchanger.

I suspect the previous home owner might have changed the high limt explaining the clearnce problem. The range is 135-175 DegF and set at the 175 DegF mark.

Can someone confirm this range is correct. I have not been able to find this information on the net.

Thanks for your help.


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## Plumber101 (Feb 25, 2009)

Did the control board have diag LED?

Can you post pic of the high limit that you have?


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## Homer-Cristian (Feb 28, 2009)

Yes I do have the diagnostics. Flashing 4 times - High Limt open.

Here is a pic.

Thanks


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## Plumber101 (Feb 25, 2009)

I think that is right. Needs to be set at 175. I'm not 100% sure I can call in monday to confirm. If you would like please post model and serial numbers.
This comfortmaker is an inner city which is alittle before I started selling comfortmaker. Comfortmaker is now made by International Cooling Porducts.


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## Homer-Cristian (Feb 28, 2009)

Model
GUI075A012IN

Serian Number
L923387610

Mnf No
GUI075AEIN

Thanks a lot for helping.


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## Plumber101 (Feb 25, 2009)

Was the filter of evap coil dirty?

Do you have a thermometer with a 5 or 6 in probe that will go up to 200 deg?

Do you know which is your return air and supply air ducts?

If so take the thermometer and make a hole in the 3 ft from the furnace return opening and 3 ft from the furnace supply discharge big enough for the probe to be inserted.

Measure each then substract the return from the supply. The difference should be about 45-50 deg

Example if return is 50 deg and supply is 100 deg then there is a 50 deg temp rise of 50 deg Delta T

I just want to make sure that you don't really have a high limit issue.


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## Homer-Cristian (Feb 28, 2009)

Filter and evaporator coil were caked. The filter is cleanable it got it clean. I used a vacume cleaner with the soft brush attachment to clean the coil. Its hard to tell if I got everything because I can only see the coil at an angle.

I tried the temperature test.

Reading 70 DegF return air at the filter.

Reading 130 DegF leaving the unit (after evap coil)

The high limit tripped again when the supplty temp was 130 DegF. 

Because the existing high limit was touching the heat exchanger there were phisical marks on the switch. It still opens high and closes low but I think my next step is to replace it with a new one. I have seen them for about $25. That is why I need to confirm the range is correct.

The temperature test makes it look like the switch is way off or the evaporator coil is still very dirty in between the fins.


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## Plumber101 (Feb 25, 2009)

I took a second look at the limit. That is a universal limit and not the one it should have. Below is what you should have. There isn't any pic but I think it is a camstat limit. I will check Monday.


Also, the temp rise is a little high for me. When I set up a furnace I set them up at 45-55. There is a sticker inside the furnace that has temp and gas specs. I think on this furnace temp min and max are 35 to 65. 



If you need I can get you a price on this part or depending on your location I may be able to tell you where you can get it cheaper.



















_*Here is the information you requested.*_*To order, click on the add to cart button.* *







* *Success, we found the genuine replacement part!* *Part Type* *Fan Limit* 







​ *Description*
FAN LIMIT 
* Our Part Number*
Use this number to order online. Receive additional discount and free shipping
  *Z1-GUI075A012IN-31CMW
* * Price * *$166.01* *Available* *Yes-In Stock* *Additional info* *FAN LIMIT CONTROL STAT 
 FREQUENTLY ASKED QUESTIONS-CLICK HERE * *







  Rush delivery available!*
*  Click here to email parts if you have any questions.*


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## Homer-Cristian (Feb 28, 2009)

Wow I thought I was looking at a $25 part.

I live in Sterling VA 20165

There is a Grainger supply house close and they cary stuff like this. There is also an Aireco HVAC supply house near me.

How did you figure out what part number I need, I had no luck.


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## Plumber101 (Feb 25, 2009)

I went to my dealer site. The age of your furnace wasn't there but I did some looking st some comparable furnaces. Because something about the limit judt didnt look right.

Then I google'd "comfortmaker furnace parts"

I looked at several sites and camstat kept coming up. The problem that needs to be answered are;

1. Determine right limit
2. Determine lenght of limit. ie. 6", 8", 9" and so on

With the wires on the limit you have this has me a little stumped. usually there are 2 or 4. you might look at the wiring schematic on your furnace. There seems to be some aftermarket engineering.

It look something like this








*Specifications:* 
Range voltage from 24 Volt - 120,240 Volt. 
7" Insertion 
WIRING CONNECTIONS: (C) COMMON, (NC) NORMALLY CLOSED, (NO) NORMALLY OPEN 
Temperature Range:120-250 F 
Differential Range: 20-40 F



I may be off base but what you have is not right.


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## Plumber101 (Feb 25, 2009)

Just FYI

ICP or International Cooling Products is basically Carrier

ICP also makes Comfortmaker, Tempstar, Aricoair

So if in your area you can find one of the above they will be able to get this part.


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## Homer-Cristian (Feb 28, 2009)

Just on the other side of the high limit is the center heat exchanger. The existing limit is only about 1/2" depth and it was touching the heat exchanger metal. My high limit is a snap disc type. It is the size of about a quarter-1/2" depth.

Nothing longer would work. 

The wiring matches the factory diagram. The limit switch really only has two terminals. There are three wires because one side of the switch has a double blade connector which gets 24v from main controller and one branch goes to the blower DP switch. The other end of the limit switch goes back to the main controller.


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## kenmac (Feb 26, 2009)

I agree with plumber. I don't know of any manufacture that used a snap disc type limit (like the one pictured) for the conbustion chamber. I have used them on floor furnaces Not a forced air furnace


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## Plumber101 (Feb 25, 2009)

Called in this morning and the limit you need is part # 1320361 my cost is $20.

If you can find a Tempstar, Aricoair, Heil or Comfortmaker dealer and give them that part number they should be able to help you.

This limit is for 230 deg +/- 20

Hope this helps


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## Homer-Cristian (Feb 28, 2009)

Plumber101

You are the man!

That explains my tripping. There is a spec on the unit which shows the 230 DegF but I thought that was some kind of manufacturing rating.

I will look for the part locally.

Thanks:thumbsup:


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## firebug2110 (Jan 5, 2010)

*Need help*

I have the same furnace and there is a flashing red light that flashes 6 times. My furnace turns on, all flames come out of the three pipes and then shut right off. I am freezing, with over a foot of snow outside I need help.


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## caribeso (Dec 10, 2013)

*comfortmaker RPJ II fan sensor*

i know this is an old thread, but maybe someone will help
my furnace exhaust fan will turn on, ignition coil heats up, gas lights, but then it runs for a LONG time and never turns on the blower fan. i have heard that the sensor for the fan might be a three pin radiant heat sensor, and no longer available. is this what i need, or is there a window i have to clean or something? thanks


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## yuri (Nov 29, 2008)

post 2 pics of it with both doors off. that unit should have a circuit board that turns on the fan or a fan timer circuit board in the fan compartment. if the fan does not start then either may be bad or the fan motor or capacitor is shot. does the fan run when you turn it to ON at the thermostat if you have AC. that furnace is very prone to cracked heat exchangers and the copper rivets that hold it together popping and causing the same problem. not worth spending a lot of $$ on repairs IMO. google cracked heat exchanger>Images.


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## caribeso (Dec 10, 2013)

*Hmmm... working now (for how long??)*

it definitely works with the fan in the on position on the thermostat

well, as i poked around, i noticed a loose wire on the top little control box. in the first photo 3414 it is the bottom fat wire on number 3. there is a chance that i pulled it off, b/c i had taken the hi limit sensor out to test it. [btw it tested closed, and when i put a lighter to it it went open, so i guessed it was OK]. so i tried to put the loose wire i found in the bottom slot of number 2, which didn't help. when i switched it to the bottom position as in the current photo, heater worked, but i had also done some other things (like replace batteries in thermostat..). however, i doubt i pulled that wire loose when i was messing with the sensor, b/c once you put it on one of those terminals, it is pretty hard to remove. so maybe this wire was just barely sitting on the terminal to begin with, accounting for intermittent operation. i noticed in another person's post about intermittent hoodoos in his furnace. 

one good thing that came out of all of this is i noticed that the pop out panel on the bottom of the heater had partially popped, and the heater doesn't sit directly on a flat surface, so maybe i was pulling in cold unfiltered air from the attic. fixed it with a bit of foil tape.

i certainly hope i don't have to replace this whole furnace, it is in the attic of a 100 year old house, with only a SMALL access panel up into the attic. not really sure how they got this one up there unless they did it during renovation.

so how do you know if your heat exchangers are cracked without taking the whole thing apart? gas exhaust smell coming thru the vents?

thanks for your help


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## yuri (Nov 29, 2008)

when they crack then flames will start coming out the front and there is a rollout switch above the burners that shuts it off. by then the furnace is unsafe. pulling the fan out and checking for missing copper rings laying in there is one method. the other is cutting a hole in the plenum and an EXPERIENCED tech will know where those exchangers fail at the bottom and where there is a burn pattern. I have a method of putting a digital thermometer by the rollout switch and starting the unit. after 5 mins if it is cracked then the temp by it will rise quickly to close to 300F and that indicates it is cracked and further checking is required. requires quite a bit of skill to know where to put that thermometer to not get a false reading etc. it's days are numbered. if it lasts the winter it may be a good idea to replace it next summer.


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## caribeso (Dec 10, 2013)

this thing is starting to really piss me off.
sometimes the exhaust fan runs, sometimes the glow plug lights up, sometimes the burners ignite, sometimes the blower fan comes on, but all in different combos. it does work at least 50% of the time, tho i think it seems to take a long time after burners ignite for the blower to come on if it does, about 2 or 3 minutes. sometimes the blower goes without any heat at all. sometimes the glow plugs are glowing but burners don't ignite (i slammed the side of the furnace in frustration once and sure as hell they ignited, not sure it was a co-incidence..)
is this a messed up circuit board or something?
multiple sensors messed up?
goblins in the attic?


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## Patrick Eubanks (Oct 6, 2011)

I am very familiar with your furnace caribeso and I can confirm that it can be frustrating. It sounds to me like its the control board and, if im not mistaken they don't make that board anymore. The replacement board is a universal board and is time consuming to install. You may want to call in a pro on this one. Installing the new board will require the ability to trace control circuits and install on the correct pins on the new board.
Good luck.


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## caribeso (Dec 10, 2013)

ug. i think i read that somewhere else, that this wasn't the greatest furnace ever made, and mostly discontinued. trouble is, it works now n then on heat, and no problems with AC. yet... 
and is in the attic of a tall old 2 story thru a NARROW hatch. almost worth going up there every morning and give it a kick to get it started... 
thx for reply, even tho not so good news...


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