[Onefastdak]

The blower runs continuously after the new board install. I did some checking with my volt meter and here is what I have.

On the low voltage block
R - 24v
GH - 24v
C - is grounded

On the rest
PR 1 - 0
L1 - 120
L2 - 0
PR2 - 0
Com - 0
LO - 120
HI - 0
Gas1 - 0
Gas1 - 0
Gas1 - 0
LIM1 - 26
LIM2 - 24
Sec1 - 26
Sec2 - 0

Any Idea what is tripping the blower? Also is there anywhere that I could find out what all of these abbreviations are so I know for future reference?
Thanks in advance.

[wmproop]

Has the tstat been ruled out? Are you setting it on auto? Not fan,, most people hate getting this question,but,not being there all possibilitys have to be checked out,, have you disconnected the tstat wires from the furnace? And does it still run continuously ?

[Onefastdak]

I tried disconnecting all of the thermostat wires and it still runs continuously. There is also a test jumper on the new board so I tried that also.

[dank1j]

Having similar issues with a 302075-302 replacement.
Initial problem was constant fan on even with t-stat off.
But A/C would work.

Now A/C does not work (compressor won't come on) and no
Cool air and internal fan runs continuously.
No voltage R-C
30 VAC across sec-1 and sec-2 which is high.

The fuse seems to be fine and the limit switch and fuseable link seem to be fine.

Thanks for any help.

[dank1j]

having similar issues with a 302075-302 replacement.
initial problem was constant fan on even with t-stat off.
But A/C would work.

Now A/C does not work (compressor won't come on) and no
cool air and internal fan runs continuously.
No voltage R-C
30 VAC across sec-1 and sec-2 which is high.

The fuse seems to be fine and the limit switch and fuseable link seem to be fine.

thanks for any help.

This guy (me) doesn't know what he's doing.
The fuse was blown and it blew again on a new one.
Replaced with a 5A fuse (not 3A) and it is working for now.

If no other ideas come in, I'll order the transformer and
Put the 3A fuse back in to test.

Any help is appreciated.
Thanks.

[wmproop]

(quote)If no other ideas come in, I'll order the transformer and
Put the 3A fuse back in to test.

Not sure why you wanting to replace transformer
If the transformer was bad,seems to me nothing would be working
Sounds like a low voltage short,either the wiring or bad contactor

[KISS]

Probably JW-1 needs to be cut/removed.

See: http://www.icmcontrols.com/downloads/icm271_ag.pdf

[dank1j]

Probably JW-1 needs to be cut/removed.

See: http://www.icmcontrols.com/downloads/icm271_ag.pdf

Cutting jw1 doesn't seem right:
2. If the JW1 jumper is cut, a constant low-speed blower will occur without any thermostat signal. Also, a signal applied to the GC or Y terminals will not bring on the hi-speed blower during the cooling mode. Therefore, the JW1 jumper must not be cut on cooling applications.
Thanks.

[dank1j]

(quote)If no other ideas come in, I'll order the transformer and
put the 3A fuse back in to test.

not sure why you wanting to replace transformer
if the transformer was bad,seems to me nothing would be working
sounds like a low voltage short,either the wiring or bad contactor

Thanks for the help. It is appreciated.
Well I got the transformer in and will try to install later today.

So, we'll know more then. If a short is the problem wouldn't the
5A fuse blow as well? It worked for an hour long test w/ the 5A in
And the 3A blows almost immediately.

The old transformer might always have run at 30V on the SEC and the old board didn't have the fuse to blow. I don't have the knowledge to calculate the 24 v 30 V difference in current, so I don't know for sure that it would blow the 3A but not the 5A.

[KISS]

Good point!

From the mnual:

If the old Carrier/BDP unit has (2) black relays just like the ICM271, then look for the JW1 jumper and R17 resistor on the Carrier/BDP board. They will be in the same location as the JW1 and R17 on the ICM271. If either one (JW1 or R17) has been cut, then cut the ICM271 equivalent. This will match the original Carrier/BDP blower speed option.