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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 21998
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a Honeywell ct3500/ct3595 and the heat suddenly stopped

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I have a Honeywell ct3500/ct3595 and the heat suddenly stopped working. I called customer service and the guy told me it was wired incorrectly; however, it had worked perfectly all last winter. He basically told me that it needed to be replaced, but I'm questioning the guy's knowledge as I was put on hold multiple times and he didn't sound too knowledgeable. When I replaced the batteries it was set to "heat" and the fan comes on, but only when I change the settings to "off" and the fan is "on." Is there anything else I can do, or am I screwed?

My name is Billy/

Do you gas heat or heat pump?


Customer: replied 2 years ago.

Gas heat

thank you...remove the wire from R and the wire from W in the thermostat. Twist them together and tell me of furnace comes on

Customer: replied 2 years ago.

It didn't work, and I think I felt a slight shock

Ok...this means the issue is withthe furnace...not the thermostat.

What is furnace make/model?

Customer: replied 2 years ago.

The furnace was just replaced in 2002, it's a Rudd Achiever 90 Plus with dual climate control

Thank you,

does this system have ac also?

If so...twist the R wire and the G wire this time...tell me if main fan starts like for cooling

Customer: replied 2 years ago.

When it was wired as it was, the fan would go on if i turned it to "off" and "fan on." The fan turned on immediately after I put those wires together



so we know we have power and the blower function works.

Now we need to twist the R and the W again...and go to furnace and tell me if the draft fan is running

Customer: replied 2 years ago.

Do I need to put the faceplate back on after twisting together?


no..when twisted together we are bypassing the thermostat totally.

So just r to w direct bypasses thermostat ,,,no need to reassemble

Customer: replied 2 years ago.

It doesn't sound like any fan is running. There is a green light blinking inside and it sounds like a computer when it's thinking.

Thank you.

Can you tell me:

What the light pattern is blinking?
Is there only one light blinking?
What is the model number inside the upper section? Starts with a RG**
Customer: replied 2 years ago.

I couldn't find the RG** number, maybe you can tell me specifically I'd look for it? There is one light constantly on, and to the left of that one, the light blinks four times, then goes off for a few counts, and then repeats the pattern. There appears to be a light that doesn't blink immediately to the left of that one.

Thank you.

The code is telling us the pressure switch is not closing. This switch closes with air flow from the exhaust fan.

So the board thinks your exhaust is running but the switch is not closing...but the exhaust fan is not running.

It is either seize/stuck
getting power but is bad
not getting power.

How far do you wish to go on internal furnace checks and voltage checks?


Customer: replied 2 years ago.

I want to do as much as I can so that I don't have to pay someone to come here and cost me more money


Ok, the exhaust fan motor warm/hot while r to w is connected together?

Customer: replied 2 years ago.

Where is the exhaust fan motor?

upper section...remove the doors. It is attached to the vent pipe that goes outside, but is inside the upper compartment of the furnace
Customer: replied 2 years ago.

Nothing in there is hot. It seems as though for some reason a cap to a pvc pipe coming out of the furnace has been removed, would that have anything to do with it?

Do you see the motor? or have you seen a model lable yet?

Customer: replied 2 years ago.

I can't seem to find the RG** number, but there is a label that has a bunch of information including the model number: UGRK-06EMAES

That was it..Rheem is also Rudd and use U and R for first numbers.

This is a pretty high tech unit.

The exhaust fan iss the black unit shaped like a big snail shell

That is the part we need to find out why it is not running.

Customer: replied 2 years ago.

okay, how do we do that?

Off to the side of the snail you see a part the size of a hockey puck turned sideways with a rubber tube the size of a pencil attached?

Customer: replied 2 years ago.

To the left of the snail shell are two white cylinders, one in front of the other, from those is a red tube the size of a pencil that goes into the bottom of the snail shell.


Turn power off.

remove the rubber tube and make sure clear..blow air through the tube back into furnace...tap the 2 white cylinders a couple times.

Turn power on.

Tell me if exhaust fan starts

Customer: replied 2 years ago.

How do I turn it off?


Power switch on side of furnace?

Customer: replied 2 years ago.

The power switch was inside the box. I found it and shut it off, there were two tubes, one coming out of each white cylinder, they each had a black tube going into a red one...i unplugged all of the tubes, blew through them all, tapped on the white cylinders...turned it back on...nothing.

do you still have 4 flashing lights?

Customer: replied 2 years ago.

I had no lights, until I pressed the button that would be pressed while the cover is on...then the fan turned on

Ok put doors back on and tell me if the unit starts now.

Customer: replied 2 years ago.

I put the doors on, as soon as the top door went on, the flame started and the heat is on

Great, we had a stuck pressure have freed it up now.

Now put wires back on R and W...then try with thermostat...I think we got it...


Customer: replied 2 years ago.

It's working! I feel so accomplished and manly. Thanks for all the help. I'm going to throw in some Red Man and watch NASCAR.

Well done!

You have completed a furnace repair many cannot.


Customer: replied 2 years ago.

My voice just dropped an octave and hair is bursting through the pores on my chest. Thanks again! You'll be getting good reviews!

Thank you...nothing like a boost of testosterone saving a service call,,Smile


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