Heat Pump Not Cooling in Pleasant Hill, CA

Heat Pump Not Cooling in Pleasant Hill

A heat pump cools with the same refrigeration cycle as an air conditioner. It adds a reversing valve so the equipment can heat in winter and cool in summer. When a Pleasant Hill heat pump runs but will not cool, we diagnose it the way we diagnose any failed AC and then check that reversing valve, the one component an AC does not have.

Pleasant Hill sits inland in the Diablo Valley, so summers get hot and the cooling side of these systems carries a heavy load. That heat is what exposes a marginal heat pump. The older Gregory Gardens and Poets Corner ranches run their ductwork through tight attics and shallow crawl spaces, where airflow problems and condensate issues are common, while the newer Hidden Lakes homes lean on multi-zone systems with dampers and control boards that can fail in their own way.

A heat pump that runs but will not cool almost always has one failed part, not a dead system. Even on a 20-to-30-year-old install, finding the broken link is straightforward once we read the system, and the fix is usually a single component. We diagnose it and put the repair and the price in writing before we start.

Common causes

Reversing valve stuck in heat mode. This is the failure a straight AC cannot have. The valve that switches the system between heat and cool can stick, or its solenoid coil can fail, leaving the unit running in heat on the hottest afternoon of the year. We read line temperatures across a mode change to confirm it. A failed coil is a smaller repair; a stuck valve body is larger, and we tell you which one you have before any work.

Failed run capacitor or contactor. In Pleasant Hill heat, this is what we replace most. A degraded capacitor leaves the compressor or condenser fan straining to start, so the system runs without cooling, and the contactor that powers the outdoor unit pits and burns over time. We carry both on every truck and meter the capacitor rather than guessing.

Low refrigerant from a leak. Low charge makes the system run constantly and cool poorly right when you need it most. On the flatland ranches, leaks often sit at line-set joints in tight crawl spaces. We pressure-test, find the leak with detection or dye, repair it, and weigh in a correct charge. A leak left alone runs the system low again by next summer, so we fix it instead of topping off.

Dirty outdoor coil. A condenser coil caked with dust and yard debris cannot reject heat in hot weather, so the house never cools even with the unit running. It is the cheapest fix on the list. We clear the airflow path, wash the coil properly, and recheck operating pressures to confirm the system recovers.

Frozen indoor coil from low airflow. A clogged filter or a weak blower drops airflow across the indoor coil until it ices over, and ice does not cool. In the older ranches with tight attic ductwork, airflow restrictions are common. We thaw the coil, find the airflow problem, and fix the cause so it does not re-freeze the next hot day.

Zoning damper or control-board fault. In the newer Hidden Lakes multi-zone homes, a stuck damper or a failed zone board can leave part of the house with no cooling while the equipment runs fine elsewhere. This looks like a system failure but is isolated to a zone. We test the dampers and the controller to separate a zoning fault from an equipment fault.

How we diagnose it

Confirm the thermostat is set for cooling and sending the correct reversing-valve signal before opening equipment.
Test the run capacitor and contactor at the outdoor unit with a meter, since these are the most common heat-season failures here.
Read line temperatures and pressures across a mode change to verify the reversing valve is shifting into cooling.
Inspect the indoor coil and filter for ice and the tight-attic ductwork for airflow restriction.
On Hidden Lakes multi-zone systems, test dampers and the zone controller; pressure-test the charge and find any leak rather than topping off.

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

Heat Pump Not Cooling in Pleasant Hill: common questions

How quickly can you get to Pleasant Hill on a hot day?

We work out of San Ramon and cover Pleasant Hill from Gregory Gardens to Hidden Lakes. Same-day is best effort, not a guarantee, but a no-cooling call during a hot stretch gets priority. The most common heat-season fix is a capacitor, which we carry, so many of these calls finish in one visit.

It is in the 90s out and my heat pump runs nonstop but barely cools. What is that?

Constant running with weak cooling in real heat usually points to a low refrigerant charge, a dirty outdoor coil, or a frozen indoor coil from low airflow, all of which make the system work hard for almost nothing. We pressure-test the charge and check both coils, find which it is, and put the repair on a written estimate.

Only part of my Hidden Lakes house cools. Is the heat pump dead?

Probably not. When one zone stays hot while the rest of the house cools, the cause is usually a stuck zoning damper or a zone-control fault, not the heat pump. We test the dampers and controller to confirm. A real equipment failure, like a stuck reversing valve or low charge, affects the whole house, and we diagnose it on that basis.

Nearby and related

Heat Pump Not Cooling near Pleasant Hill: Walnut Creek · Concord · Lafayette · Martinez .

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