Said It Here

Furnace won't turn on after new AC installation

The gas valve may have been left closed or something was missed during the recent HVAC installation, preventing the furnace from starting up when the weather turns cold. Homeowners worry that waiting too long to report the issue will make the warranty company or contractor upset about the delay.

Overview
People affected4 accounts across 1 forum
Workarounds found7 items attempted
Community agreement2 total upvotes

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

7 items+ Contribute

Found another way around this?

Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.

  1. 1
    Checking the door latch, suction nipple, board power, and considering bridging the R-W wires
    Did this help you?
  2. 2
    Waiting a week before opening up a service request
    Did this help you?
  3. 3
    Checking if the gas stop and service valves are actually on
    Did this help you?
  4. 4
    Observing the furnace startup sequence and inducer fan
    Did this help you?
  5. 5
    Counting flashing diagnostic error codes on the furnace control board
    Did this help you?
  6. 6
    Calling a professional HVAC technician
    Did this help you?
  7. 7
    Changing the batteries in the thermostat
    Did this help you?
Tried another approach not listed above?+ Share your workaround ↑

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/hvacadvice4 people · September 2026

“I recently. Bought this house with a 2019 airtemp furnace and its not working at all only a single green light. Anyone ever seen this before? No noises nothing.”source ↗

Commercial-Bite-1484 · r/hvacadvice · 1 upvotes

“Does it do anything when you turn it on, any noises at all?”source ↗

boqiuefieous · r/hvacadvice · 1 upvotes

“My question is I just noticed this week when it was getting cold my furnace won't turn on.”source ↗

“My question is should I wait at least a couple months to open up a service request, it seems like it will send the same company out and I am worried they will be upset I didn't notice it last month..”source ↗

NoCancel8448 · r/hvacadvice

“AI is telling me one of my gas valve are closed, I tried to start my furnace, what am I missing?”source ↗

“same guy that posted about it yesterday, just want to make sure I have the gas valves on sorry and thanks for anything comments”source ↗

RegularBlacksmith471 · r/hvacadvice

Where this came up

r/hvacadvicefurnacefurnace repairheatinghome maintenancehome warrantyhvactroubleshooting

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