lennox L series

[coilcleener]

Have a unit which has no stat or anything wired to unit yet because of construction work being done.Tetsed unit from IMC board and found that it keeps going to error code 5- which says Air Flow Switch-This indicates no blower air 16 seconds after blower demand.
Tested switch seems good, unit tests ok but wont stay in test mode very long because goes in error.
Any thoughts

[lions_lair]

most equipment mfg. ...won't warranty equipment if ran still under construction....just sayin....i cleaned a 7,5 evap coil today...took 3.5 gallons of foaminator ..and 5 rinses to clean...i should a taken pics for wall of shame....install in '06...all 74 tons had to have evap n cond, coil cleanings....hummmm...bout 3500.00...love no p/m's...got me one there now:pileon:

[hvacpope]

is a prodigy m2 control or A55?, with the A55 board the unit will stay in test mode regardless of the error codes, what are the dip switches set to? are you testing it using shift/unit test?

[coilcleener]

Yeah its an A55 board and im using shift unit test, and usually they do stay in test mode but this one will go into test mode and then show this code and cut out the unit while its running and show the error.

[cjpwalker]

blower running backwards (3 phase)?

[jmandtc]

Check tubing for blower switch. It may be out of position and not be able to sense draft of blower motor...

[hipsterdaddyo]

Check the white plug that the wires for the airflow switch connect to. Make sure they are all connected, and actually in the plug themselves. I've seen where the wires have been pulled too tight and the come out of the plug on either side. What's the model and serial number of the unit?

[hvacpope]

Check the white plug that the wires for the airflow switch connect to. Make sure they are all connected, and actually in the plug themselves. I've seen where the wires have been pulled too tight and the come out of the plug on either side. What's the model and serial number of the unit?

I've seen the same problem with the FS plug but while in test mode the control should ignore the trouble and make the unit run regardless right?

[Trevorjh101]

If the BUILDing is under Construction i would Start by checking The Phasing to the unit, reverse or incorrect phasing can cause all kinds of issues on Anything. Maybe a Blower motor running Backwards, If so the swicth will test find with your meter however its not getting the proper pressures when the blower is running to close the swicth. However those Lennox L-series Boards are Smart it may have a code # to say if the phasing is wrong, not sure. Electricans move Panels all the time during Construction and sometimes hookm up wires worng. I have just experianced that at a local superstore under Construction, there main HRV for the store was running all weird, found phasing Issue.

[hipsterdaddyo]

Make sure the tube that is actually intact IE: No cracks, tears or rips. You could also bypass the switch, check continuity on the switch while the unit is running, and see if something internally is intermittently dropping out and causing it to lockout the IMC board on alarm.