T057_F: Inducer Hi Pressure Switch Won't Close
Status
The furnace may or may not operate in gas heat modes but all other modes (e.g. cooling) should function.
Description
This fault indicates that the high pressure switch is open when the inducer is energized at high speed. If this fault persists, limited heating may be allowed on 80+ furnaces, but 90+ furnaces will not proceed wih a heat cycle until the high pressure switch closes.
Expected Operation
80+ Furnaces
80+ furnaces always ignite at low heat stage. High heating is only allowed after blower turns on and steady state heating is entered. If in steady state the demand switches to high heat but the high pressure switch fails to close, the control will declare fault "T057_F Inducer Hi Pressure Switch Won't Close" and will finish the remainder of the heat cycle in low stage heating. The fault will be cleared when the heat call is removed.
90+ Furnaces
Pre-purge: If the high pressure switch fails to close until 2-3 sec after entering pre-purge or if the pressure switch unexpectedly opens for more than 4 seconds during a pre-purge cycle, fault "T057_F Inducer Hi Pressure Switch Won't Close" will be logged within 10 seconds. The control will disregard such a pre-purge cycle, although the 34 second period will still be completed before going to the next cycle. The IFC will allow a maximum of 3 cycles for the pressure switch to close. If the pressure switch closes within 2-3 sec from the start of a cycle (or is already closed at the beginning of the cycle), in such a case, the control will complete the 34 seconds pre-purge and will go over to trial for ignition. If the pressure switch fails to close in these three cycles or closes 3 seconds after the start of the third cycle, the control will enter a 5-min lockout with "T057_F Inducer Hi Pressure Switch Won't Close" and "T047_F Inducer Fan 5 Minute Lockout" logged.
Ignition trial/blower on-delay: If the high pressure switch opens for more than four seconds during trial for ignition or blower on-delay, fault "T057_F Inducer Hi Pressure Switch Won't Close" is logged within 10 seconds and the control proceeds to post-purge and blower-off delay. A new gas heat cycle shall be initiated if the heat demand is still present. The fault will remain logged until the pressure switch closes on a subsequent attempt or the heat demand is no longer present.
Steady state heating: If the high pressure switch fails to close or opens up for more than 4 seconds during steady state, the control will declare fault "T057_F Inducer Hi Pressure Switch Won't Close" and will finish the remainder of the heat cycle in low stage heating. The fault will be cleared when the heat call is removed.
Cause
1. Blockage or improper termination in either the inlet or exhaust vents.
2. The flue vent length and/or number of elbows exceeds the maximum number specified.
3. Faulty or disconnected inducer.
4. Faulty control board (inducer relay).
5. High altitude kit not installed in areas of high elevation.
6. Loose or faulty wiring.
7. Disconnected, blocked, split or cut pressure switch hoses.
8. Wind gusts (sporadic).
9. Faulty pressure switch.
Solution
1. Check the vent system for blockage and proper termination and repair as necessary.
2. Check the specification sheets and/or installation instructions. Remove excess venting.
3. Repair or replace inducer and/or inducer wiring and/or electrical connections.
4. Replace control board.
5. Check elevation of the installation and consult the specifications for the furnace to determine if a high altitude kit is needed.Install proper kit as necessary.
6. Check wiring and connections. Replace and/or repair as necessary.
7. Replace hoses as necessary.
8. Insure proper termination and determine if high altitude kit may be necessary (see item 4)
9. Replace the pressure switch.
