[wetbar]

Hey I am working on a Goodman GPG10300701A gas pack. This started as a no heat call, when I got to customer site the limit switch in the blower was open. Went to replace it and found the wires off. I put the wires back on the switch and restarted the unit and everything worked great. Cleaned the unit for the customer and tested everything. The next morning I get a call - not working. So I go back to site and the unit is locked out. I reset the breaker and the bottom burner was not working. I test the Outlet pressure it is 8.5 I adjust it back down to 3.5 and the bottom burner comes on and runs. (I could do it the day before because my manometer broke.) So I did a combustion test just to make sure all was ok and it was. Tell the customer no charge head on my way. The next morning I get the same call. Get to unit - it is locked out again! I have checked the fan, filters, gas valve,limit switches, and roll out. I cant tell if it is a time thing or as air temp thing. When I get there and reset the unit, it worked great but it is 65 degrees outside. When it shuts off on the customer it is 45 or so and always at night.
Any clues

Thanks for the help.

 

[HVAC_Marc]

Do a full cleaning, it usually catches a lot of problems. Be meticulous. But I have this odd feeling like the homeowner was futzing with it. No gas valve gets to a manifold pressure of 8.5 by itself.

 

[jacob-k]

and both wires off the limit switch? huh?

 

[rundawg]

Hey I am working on a Goodman GPG10300701A gas pack.
The next morning I get the same call. Get to unit - it is locked out again!

What diagnostic fault code was it locked out on?

 

[captube]

Check the blower motor amp draw, capacitor etc. maybe shutting down after longer run time.

 

[Hidalgoj]

Had similar problem on a rheem problem was blower wheel was dirty.

 

[captaincompressor]

Dirty blower wheel will not scoop enough air and go off on high limit. Check the codes

 

[Snapperhead]

its shutting off at night because it runs longer due to being colder ....

sounds like a airflow issue

 

[dougfamous]

I found this thread while searching for an exploded view of your unit. The guy had the same problem and had some gasket material missing from around the burner box. Read on:

http://hvac-talk.com/vbb/showthread.php?966292-Goodman-gpg-gas-pack-pressure-problems/page2

 

[martyinlincoln]

Flame senor reading?

 

[NiHaoMike]

If the fan is not already at its highest speed, try bumping it up a speed.

 

[kimosobee]

Is this a condensing furnace or 80% or less

 

[jimj]

Check on goodmans site for any tech bulletins. I know they had some models that had to low of limits