I have a 12 year old Goodman furnace. About 3 years ago, I asked a service tech if there was anything that can be done to get warmer air out of the registers. He said he slowed the blower speed to get a higher temperature rise.

I had the ductwork replaced and it is smaller than the original ductwork and now it (the ductwork) gets pretty warm. I'd like to return the blower to its original high speed but I'm a little confused.

I guess my confusion is due to a discrepency between what's hooked to the board and what is on the schematic.

I have a Goodman GMP series furnace. Here's the color wires from the motor and what they are connected to:
White goes to the NEUTRAL
Orange is hooked to HEAT
Black is hooked to COOL
Red is hooked to M1
Yellow is hooked to M2

This is what the schematic calls for:

Wh to Neutral
BK to COOL
Red to HEAT
(*)Blue to M1
Nothing on M2

There are no Blue wires from the motor but the asterisk leads to a footnote that says "The leads from the motor may be changed to the required speed. Med HI-YELLOW; Med LOW- Orange. Remember, I'm trying to return fan to high speed to reduce temperature rise. Thanks.

Looks like Black is your high speed. It may already be used for your A/C if you have one.

If you want to use high speed for both heating and cooling, I think you could jumper the black to both heat and cool. The blower is controlled by separate relays, and I don't think the power would feed back to anything as long the other relay is open. You could also try switching Med HI-YELLOW and Med LOW- Orange. Sounds like they provide different intermediate speeds with yellow being higher than orange. The M1 and M2 may just be convenient places to keep unused wires out of trouble. See if the schematic shows anything connected to them.

This may just put the wires back in their original position.

So, let's see if I understand this. What ever is hooked to the HEAT terminal determines the speed of the blower?

And if I put red to heat as called for in the schematic, I will see a change in fan speed?

It may be more complicated than that. I forgot about red. It is possible M1 or M2 may also be activated. Does your furnace have more than one firing rate? The blower speed may vary with the firing rate. You may just have to try different combinations.

You could also use an isolation relay between heet and cool speed. I always worry about a back feed when both heat and cool are connected together to use the same speed.

It may be more complicated than that. I forgot about red. It is possible M1 or M2 may also be activated. Does your furnace have more than one firing rate? The blower speed may vary with the firing rate. You may just have to try different combinations.

No, it has only one firing rate. The blower in not variable speed. And, I believe M1 & M2 do function somehow because the furnace won't come one if they are disconnected. As if they are part of the safety circuit. It can't be too complicated.

M1 and M2 are unused speeds