Heat Pump Not Heating in Palo Alto, CA

Heat Pump Not Heating in Palo Alto

Palo Alto runs a lot of equipment that was chosen with care. The Eichlers in Greer, Greenmeadow, and Fairmeadow are on multi-head ductless mini-splits because the post-and-beam ceilings rule out ductwork, and the heritage and infill stock across Old Palo Alto and Midtown tends toward variable-speed heat pumps. When one stops heating, the cause is almost never the whole system. It is a single component.

On a multi-head Eichler mini-split, a no-heat complaint usually traces to the refrigerant circuit: a reversing valve stuck in cooling, or a low charge from a line-set leak. With several indoor heads on one outdoor unit, a fault can also show as one room warming while another stays cold, which points at a branch or a head-specific issue. On a variable-speed heat pump, a defrost control fault or a communication error between the boards is the more common story.

Palo Alto's marine-influenced winters are mild, with lows that sit comfortably inside full heat-pump capacity. A no-heat call here is a fault to diagnose, not the climate. We work to the same code-correct standard the system was installed to, and the diagnosis and price go on the written estimate first.

Common causes

Reversing valve stuck in cooling. When a head blows cool during a heat call, the reversing valve isn't switching to heating. On variable-speed and multi-head systems the solenoid coil is a common failure and a clean swap; a seized valve body is a larger job. We confirm with line-temperature readings before quoting.

Low charge from a line-set leak. Eichler retrofits route line sets to multiple indoor heads, and a slow leak at any flare drops the charge and cuts heating capacity. We pressure-test the circuit, locate the leak, repair it, and weigh in the manufacturer-correct charge for the specific system rather than topping off.

Control-board or communication fault. Variable-speed heat pumps run communicating controls between the indoor and outdoor boards. A failed board or a comm error can drop heating while everything looks powered. We pull the fault codes, check the communication line, and replace the board that's faulting.

Defrost control out of spec. Palo Alto's foggy winter mornings frost the outdoor coil. A failed defrost board or sensor lets frost build into ice and heating falls off. We observe a defrost cycle and verify sensor resistance, then replace the part reading wrong.

One head cold on a multi-zone system. On a multi-head Eichler system, a single cold room while others heat points at a branch-side issue: a clogged or failed head, a stuck expansion device, or a partial blockage to that branch. We isolate the affected head and check it against the others to find where the circuit is starved.

How we diagnose it

Confirm the heat call and observe each indoor head's output, important on multi-zone Eichler systems.
Pull fault codes and check the communication line on variable-speed and communicating systems.
Read line temperatures and pressures to separate a charge problem from a reversing-valve problem.
Pressure-test the circuit and inspect line-set flares to the heads for slow leaks.
Run a defrost cycle and verify the board and sensor against spec.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

Heat Pump Not Heating in Palo Alto: common questions

Do you service Palo Alto, or only the East Bay?

We cover Palo Alto and the Peninsula daily from our San Ramon base. No-heat calls get priority scheduling, and we target same-day where the route allows, though same-day is a best effort, not a guarantee. Call (925) 999-4095 for a real time window.

My Eichler mini-split heats some rooms but not one. Is the system failing?

Usually not. One cold head while the others heat points at a branch-side issue: a failed head, a stuck expansion device, or a partial restriction to that zone. The outdoor unit and the rest of the system are typically fine. We isolate the affected head and find where the circuit is starved.

Is the mild Palo Alto winter ever the reason a heat pump won't heat?

No. Our winter lows sit well inside full heat-pump capacity. A no-heat call means a component failed, the reversing valve, the charge, the defrost control, or a communicating board. The climate isn't the cause here.

Nearby and related

Heat Pump Not Heating near Palo Alto: Menlo Park · Los Altos · Mountain View .

This is usually a heat pump installation & service in Palo Alto job. See our heat pump installation & service overview or the Palo Alto service area.