Heater fuse blows when ac is turned on

SOURCE: 3amp fuse keeps burning out

That fuse should be a 3 amp fuse. There is either a problem in your wiring, your A/C contactor or the board.

SOURCE: The Exterior Units does not turn on.

It sounds like the outdoor unit is tripping on high pressure. This can be caused be a dirty outdoor coil. It can take hours for the unit to reset and try again. a loose or damaged control wire can also cause intermittent power loss as you have described. With that said I suggest that you call a technician to check it out.

SOURCE: Goodman a/c works, heater will work fine then fan will stop

you have a circuit board acting up. Try keeping the fan in the "On" position. It will keep the blower on all the time but it may work. There is a built-in delay not allowing the unit to come on after you reset it with the thermostat, wait three minutes or so to see if it comes back on. I still suspect a bad circuit board.

SOURCE: my fridgidaire gas furnace is blowing cold air

Today’s furnaces are controlled by a computer which constantly monitors for problems. When it detects a problem it will shut off the burners. Depending on the problem and the specific furnace it will either “lock out” the furnace or cycle it through a purge (to rid it of un-burned gas and excess heat) and then attempt to re-start it. If the problem continues to occur then it will “lock out”. Depending on the problem and the furnace it may again attempt a re-start after several hours. In any case if the problem was not detected/caused by a sensor which requires a manual re-set, when the power to the computer is interrupted or the call for heat is interrupted the computer is reset and it will again attempt to re-start the furnace. The most common problems are:
· Low or lack of flame sense. Different furnaces use different methods to detect a flame – often these “flame sensors” become dirty and have to be cleaned (usually with sandpaper or steel wool).
· Bad igniter. (Doesn’t light at all).
· Clogged combustion air intake or exhaust.
· Clogged condensate drain. (90+% efficient furnaces).
This is not a complete list, only the most common!
Depending on where you live your HVAC system runs more than anything else you own (including your car). All furnace manufacturers “recommend” “regular maintenance” of your furnace. In fact, all that I am aware of state in their warranty that the warranty may be voided due to lack of “regular maintenance.” The industry has defined “regular maintenance” as yearly (in fact, some manufacturer’s warranties state yearly). Due to safety, liability, and the need for many other things to be checked, cleaned, and/or adjusted (2-page checklist where I work) to ensure safety and efficiency. Due to the large number of furnaces and the differences between them. Moreover, due to the terms of this site, I WILL NOT AND CAN NOT give you specific instructions on how to perform repairs on your furnace. I suggest that you contact a local, reputable, HVAC service company for (a tune up, preventive maintenance, general maintenance, yearly service call, general service, or whatever they call it).

While I may not have told you how to fix your furnace yourself, I have told you how to fix it. Please rate my answer.

SOURCE: Goodman GMS90703BXA Heater/AC - 3 Amps Fuse blows

It is a problem on your low voltage side. I had the same issue and found that my wire going to my outside condeser had been snagged on a wire hanger in my basement and was shorting out the system. I went a head and replaced the entire wire from my outside unit to my indoor and haven't had an issue since. So my advice is go to HD or Lowes and purchase some 14 gauge wire and replace the low voltage wire. If that doesn't work, then replace the thermistat wire, and thermistat. Great time to upgrate to a energy efficient thermastat.