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Board repair

HVAC Control Board Repair — Rooftop Units and Furnaces

A rooftop unit puts its control board through the full temperature range twice a day, with vibration from the blower and whatever the local power does in a storm. Boards that fail there rarely fail cleanly.

Book a board inRates and terms

$85

Bench diagnosis

Credited when the repair is approved

$1,200–8,000

Typical replacement

What the OEM board costs new

10–25%

Repair cost

Of the replacement price

1–3 business days

Turnaround

Bench time, plus transit. 90-day warranty.

What to send

Boards handled in this category

Send the board, not the equipment. If the board you have is not on this list, send the part number and ask.

  • Integrated furnace controls and ignition modules
  • Heat pump defrost boards
  • Blower and ECM interface boards
  • Economizer and damper controllers
  • Rooftop unit control and lockout boards
  • Thermostats and zone controllers

Symptoms

What it looks like from the equipment side

These are the faults that most often turn out to be the board. None of them prove it — that is what the diagnosis is for.

  • No heat or no cool with the thermostat calling
  • Lockout after a set number of ignition attempts
  • Blower runs continuously, or will not start
  • Unit short-cycles on and off
  • Heat pump will not come out of defrost
  • Board dead entirely after a storm

Failure modes

What actually fails, and why

Common to this class of board. The cause matters as much as the fault — a board replaced into the condition that killed it fails again.

Surge damage on the 24 V control circuit

A nearby strike does not need to hit the unit. The 24 V side takes the transient, the protection component does its job once and dies, and the next surge goes straight through.

Flame sense and ignition drive circuits

Flame rectification works with microamps, so a leaky component or a contaminated board surface is enough to make a good flame read as no flame. The result is a lockout with nothing visibly wrong.

Cracked solder joints

Blower vibration plus daily thermal cycling cracks joints on heavy components — relays, transformers, connectors. The fault is intermittent and moves when the board is flexed, which makes it maddening in the field and straightforward on the bench.

Relay and contactor driver failure

A shorted contactor coil takes out the driver switching it. Replacing the contactor without checking the board leaves half the fault in place.

Failed supply capacitors

Rooftop heat cooks the supply section. The board works cold and misbehaves once the cabinet warms up, which reads as a mechanical fault until someone measures the rail hot.

Mail-in

Getting the board to the bench

Book it in first. An RMA number comes back the same business day, and the board arrives with the paperwork already attached to it.

Ship to

System Voidz — Repair IntakePO Box 33 (USPS)413 Railroad Ave (UPS, FedEx)Watrous, NM 87753

Use the PO Box for USPS and the street address for UPS or FedEx — a PO Box cannot accept courier deliveries.

Wait for the RMA number before shipping.

Before you pull it

  • Photograph the board in place, connectors attached. It is the single most useful thing you can send.
  • Note the equipment make and model, and the number printed on the board itself.
  • Write down what it was doing when it failed — intermittent, heat-related, or after a storm all change what gets tested first.
  • Pack it in an anti-static bag. Bubble wrap alone is not enough.
Book a board in

Questions

HVAC and rooftop units — common questions

The board is under warranty from the OEM. Should I still send it?

If it is genuinely under warranty, use the warranty — that is the cheaper route and it is what it is for.

Repair is the better answer when the warranty has expired, when the board is discontinued, or when the replacement is quoted on a lead time you cannot wait out.

It only fails when it is hot. Can you find that?

Yes, and that is one of the more common patterns on rooftop boards. Intermittent-when-hot points at the supply section or a cracked joint, both of which show up on the bench under heat.

Tell us it is heat-related on the intake form. It changes what gets tested first and it is the sort of detail that saves a day.

Do you work on the unit itself?

On-site work is available across northern New Mexico. Everywhere else is mail-in, board only.

For a rooftop unit the board is almost always the right thing to send — it is the part that fails and the part that is expensive.

Also repaired

Other equipment

Component-level repair is the same discipline across all of it. Only the failure patterns change.

$85 bench diagnosis

Send the board before you buy a new one.

Diagnosis is $85 flat and is credited when you approve the repair. If the board turns out to be good, you have ruled it out for certain and paid the diagnosis fee only.

Book a board inCall (505) 309-0534