I have a frideadaire r4 series furnace my control board went bad I replaced my board a
A 624591-b with a icm2508 or 903106 now the new board is giving a message status light message of 115 vac
And neutral reversed or no ground there is no reversal and I have ground on pin 9 I am at a loss
What to check next.

When they say ground, they mean a dedicated ground from the breaker panel to the furnace. So if you don't have a ground along with your hot and neutral to the furnace, the new board is letting you know that. Also, have you check polarity to make sure the hot and neutral are hooked correctly? Just because the old board worked, doesn't mean the new one will if polarity is wrong. So basically, if the board is telling you it polarity or ground, then its one of three things. 1. reversed polarity. 2. bad, or no ground. 3. Defective board (giving incorrect diagnostic, which is not unheard of, but very uncommon).

Double and triple check your polarity with a volt meter, and make sure there is a dedicated ground to the unit (you can have all kinds of ground wires in the furnace, but if the furnace itself isn't grounded, they do no good.) Check these things and please do let me know what you find. Best of luck, take care.

Grounded yes
115to positive
115to neutral

I do believe. Everything is hooked us properly. I do not know how to check polarity on vac If I switch there two wires both of which go to its own 30amp fuse in the fuse box would it make a difference would it fry the board

mygirlsdad77 I still have not figured it out I do not know how to check polarity on vac115 dc sure but not a c
I have tracked both wires from the power supply back to the fuse box both black and white wires connect to its own 30 amp buss fuse so 2 fuses and the ground connects to the ground bar in the fuse box and test
Clean any ideas

There should be only one wire to a fuse, and one to the neutral bar. Are you saying you have 240v at the furnace? It may be time to have a tech come look things over. Hard to say for sure what you have from here.

If you only had one wire hooked to the fuse, and the other to a nuertal bar, then you would want the one from the fuse to the hot on the furnace, and the other to the neurtral at the furnace.

Make double sure you traced the wires correctly, cause it sure sounds like you are looking at a 240 connection in the fuse box. Just tough to guess what they may have done back when the house was wired (and if you still have a fuse box, that was a long time ago). Just can't guess on this without seeing it first hand, sorry.

PS. To check for polarity at the furnace, you would simply unhook the supply voltage wires, and test from one at a time to ground. One should have 120v, and the other should have 0v. 120v is your hot, and 0v is your neutral.

It was a bad new board all good now

Thanks for the update. Glad you got it fixed.