Back in the spring, my 1987 Carrier Vertical GFA system wouldn't fire up. I saw that after the HSI didn't come on, it went into shutdown mode. I figured I'd replace the HSI before fall.
Now, $30 later, the new HSI still won't fire up. The draft induction motor starts, but no HSI. Could this problem be in the control module? Is there any suggestion for giving it another DYI repair before I call in a pro? Any links? Thanks.
Hi, You should hang a meter on the HSI connector to read 120V AC before replacing it.(I keep a spare HSI all the time) What is error code? If HSI does not glow it is not getting the 120V it needs on time. Control board may have a cold solder joint due to heat. Or relay which switches HSI power is not working. In this case it could be relay itself or logic signal controlling it. I have a same family furnace here and went thru logic board once so I am quite familiar with it. Again, what is error code? One thing I can suggest you off my head is flip the board over and look carefully under the two high Wattage resistors to see if the solder joints is cracked due to heat. I mean hair line crack. Wiggle the resistors to confirm it. If indeed tha's case, resolder the joint and drill couple holds around the resistor on the plastic cover for good cooling. BTW, manual has trouble-shooting flow chart. Good luck,
Ok, I've been doing some research, and see the next thing to test is the pressure switch. I've seen some sites that say it should read 24v across the terminals when the correct negative pressure it reached. Can I get a clue where the switch is located?
Not really. There are many variables to the sequence of operation of your furnace, that you need to check.
You can keep on changing parts, until you find out what it is that is causing the problem, and even after you have replaced everything in the furnace, you might still have the same problem.
I would call a pro, since furnace repair is really not a DIY repair.
Maybe the problem wasn't a bad HSI.
If it was a newer furnace (don't know about 1987 features) I'd first check that the air filter (cold air return) isn't clogged, check that if high efficency the outside air intake/exhaust aren't blocked. And you might try moving the ignitor a tad closer to the flame ... worked for me with an older gas furnace.
Just keep throwing parts at it and listening to bogus advice from newsgroups and you'll eventually fix it.
Hmmm, If you don't know what/where pressure switch is, hmmm, it's near the inducer motor. See that little clear hose? What is error code?
Tony Hwang wrote in news:n9nAg.309509$Mn5.127815 @pd7tw3no:
ROTFLMAO!! OK, fess up..this is a test script for a new sitcom, right??? It's going to be a big hit, because it's hilarious!
Before you call in a pro, you might want to do some homework..... Consider that they only build them to last 18 - 20 years. Second, in just a little over 3 years, the R-22 equipment will not be available anymore.
Hi, Basic IQ test, LOL!
You can get a clue, or for five hundred dollars, I'll give you what's behind curtain number one!
I never said it has A/C.
As far as the other joker answers..this group is obviously a joke, just like the lives of most HVAC repairmen i've seen.
make sure your vent pipe is clogged with something if not then your gas valve maybe sticking
Hi, Last hint. You ought to get a trouble code. It fails with HSI not glowing, then after pause it'll retry and then failing again it'll give trouble code by way of blinking LED on the board. Then it goes into lock up mode. To reset you have to turn the breaker off and on. Checking pressure switch, remove the hose, check the switch with meter while you blow into the hose(some times debris plug up the hose) Again consult trouble-shooting flow chart in the manual. HSI glow sequence comes after pressure switch makes sensing pressure build up in the flue by inducer motor. Again, inducer motor runs > presure sensed > HSI power enabled > gas valve open > flame sensor sneses flame > blower starts running ........ so on and on. Good luck, Bye for now.
Its very simple. Check for 24v at the module input and 120v at the ignitor plug. If you dont have 120v at the ignitor plug and you do have 24v input to the ignition module, the module is bad. If you dont have 24v to the module the problem is in the safety or control circuit.
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