I have a Goodman GUPI100-4 furnace that won't ignite and both, the inducer fan and blower motor are running when powered on. I have tried the following to correct the problem - replaced ignitor assembly, replaced pressure switch, removed inducer fan to replace dry-rotted gasket with high-temp silicone, and visually inspected circuit board for burn marks ( there were no burns ). I checked the voltage going into the circuit board and I'm getting 24V, but I only have 6.0 - 6.4 volts coming from board to pressure switch. Is this a bad circuit board? I've also tried to put a jumper wire on the two terminals on the pressure switch and nothing happened. Can I manually operate the pressure switch by blowing and sucking air into it?

Can I manually operate the pressure switch by blowing and sucking air into it?
Watch your eyebrows.
Is there a fuse on the board?

No, there is no fuse and no indicator light on circuit board

If you have a meter you can check your HSI to see if voltage is reaching the ignitor. You can also check your limit switches for proper operation.

There is no power going to the ignitor. I'm only getting 6V at the pressure switch, which is not enough to send a signal to ignite, I'm assuming? Why would I only be getting 6V? Bad board? Thanks for your response!

You might check all your supply 120 volt wiring and make sure the grounds are good. Other than that from what you have said it could be the board. No power at the HSI means the voltage is not being sent from the board to the HSI. Does the blower fan that circulates air in the house work OK. I am just curious because if it is then proper voltage is getting to the furnace.

NOTE would you please check your model number again. I am getting conflicting diagrams one is showing you have a spark ignition module.

120V is good,transformer is good, reading 26V. The blower fan and the inducer fan are both blowing. Correct model#GUPI100-4 spark ignition

Quote:

---

Originally Posted by hvac1000

You might check all your supply 120 volt wiring and make sure the grounds are good. Other than that from what you have said it could be the board. No power at the HSI means the voltage is not being sent from the board to the HSI. Does the blower fan that circulates air in the house work OK. I am just curious because if it is then proper voltage is getting to the furnace.

NOTE would you please check your model number again. I am getting conflicting diagrams one is showing you have a spark ignition module.

---

Here is what I am finding.

That's the correct diagram

Scratch all the HSI stuff from above. You have spark ignition. If 24 volts are getting to the spark box on a call for heat and there is no spark and you checked to make the screws for the box that goes into the sheet metal of the furnace are making good contact (the screws make contact from the spark box to the furnace) then I believe you may have a bad spark box. That unit is made by United Technology and can be hard to find.

Probably looks like this.

Carrier United Technologies B13707 24 Intermittent Pilo - eBay (item 230231608842 end time May-11-08 05:06:40 PDT)

O.K. I'll do some further testing and check for a good ground. Thanks for taking your time to help, it's greatly appreciated!

Well, after replacing the air pressure switch, spark ignitor, ignition module, and control board, I STILL had the same problem. It ended up being the high-limit switch! I've learned a valuable lesson here though, start with the LEAST expensive items first. After spending 2 days and $375.00 it ended up being an inexpensive part and easy to replace! Going into this project, I knew nothing about furnaces, now I know every part and it's functions so, at least I gained something out of this horrific job! I just hope this post helps someone else out somewhere down the line, along with their money and time!

In one of my first posts to you I said to.

((You can also check your limit switches for proper operation))

Gald you got it fixed.

I have A Goodman furnace that will not ignite. The LED on the control board is stead on (indicating normal operation -- no flashes). When set up the thermostat, a call for heat seems clicking, then inducer fan is on, then seems gas is hissing for a few seconds. But the hot surface ignitor will not turn or grow red, and the furnace will not ignite. Any ideas?