Other problems that could cause the pressure switch to not open are a dirty blower wheel on the inducer.
Trane gas furnace pressure switch error.
And about 400 later the problem still existed.
Vent pressure error three flashes on the trane furnace control board means that the vent pressure is too high or too low which then activates the pressure switch and causes a lockout.
A pressure switch error on a trane furnace may lead to a very cold home if not corrected in a timely manner.
One potential error is a furnace lockout which is not something that every furnace user knows about.
This error code remains flashing through the next cycle until the moment that the furnace should activate then disengages and errors out again.
Remove the main access panel on the front of the furnace.
The pressure switch fitting may have a restrictor inside do not remove.
It should be clear.
The sensor closes when the furnace kicks in and allows heat to enter into the home.
The pressure switch is an indicator of pressure problems in the furnace.
One goes to the gas valve and the other one goes to the bottom of the furnace where the burners are.
When a pressure switch error occurs the system will shut down and no warm air will enter the home.
Inspect the pressure switch hose.
A pressure switch senses pressure within the flue system.
Trane xr 90 gas furnace that is coming up with three flashing led lights saying that its the pressure switch witch was replaced last spring the vents are open whats my next move read more rick.
If the hose is cracked replace it.
This is for anyone experiencing pressure sensor limit switch issues with the xr series trane furnaces i went the end of one winter seasons and the beginning of the next trying to resolve this issue.
Inspect the hose s connected to the pressure switch to make sure it is connected at both ends and is in good condition.
Let me clarify the bottom side of the pressure switch is the intake that has a small white flexible hose attached to it that runs down into air intake area.
Check the tubing from the inducer.
There s a motor engaging but after 5 speed ups the system disengages with the 3 flash error code for the inducer fan or pressure switch.
Also the fittings that the tubing fit into should be clear.
1 a restricted vent pipe 2 too long of vent piping and too many turns which exceeds manufacturer s recommendations 3 a stopped up condensate drain line if you have a high efficiency condensing furnace.
The exhaust side of the pressure switch actually splits into two hoses.
