RV Heat Pump Service and Repair - Mobile On-Site Technician
Coast to Coast RV Repair provides mobile heat pump service service on-site at your campground or driveway across Florida - certified technicians, same-week scheduling.
Coast to Coast RV Repair provides mobile heat pump service service on-site at your campground or driveway across Florida - certified technicians, same-week scheduling.
Certified technicians. $299 service call. Same-week scheduling. Call (866) 437-4848.
How RV Heat Pump Reversing Valves Fail in Florida Climates
The reversing valve is the component that makes an RV heat pump dual-purpose - it physically redirects refrigerant flow between heating and cooling cycles. Dometic Penguin II units use a Ranco-sourced four-way reversing valve controlled by a 12V DC solenoid coil rated at 85-120 ohms coil resistance. In Florida's high-humidity, salt-air coastal environments, the solenoid coil windings corrode from the inside out, causing resistance to climb until the coil can no longer generate enough magnetic force to shift the valve spool. The result is a unit that works perfectly in one mode but blows ambient air in the other. Coleman Mach Heat Ready units (model 47004-876) use a similar valve assembly but place the solenoid coil on the high-pressure side, making it slightly more vulnerable to heat cycling. Faults typically show up as the unit running its compressor but producing no temperature differential at the supply vent in one mode. A basic multimeter test of solenoid coil resistance - performed without touching refrigerant - can confirm or rule out this failure in under five minutes, making it one of the most straightforward heat pump diagnoses our technicians run.
Defrost Control Board Lockout Patterns on Dometic and Coleman Heat Pumps
Both Dometic and Coleman heat pump units use dedicated defrost control boards that monitor outdoor coil temperature, defrost cycle timing, and reversing valve response. Dometic's board (part 3312564.000 in Penguin II units, part 3313107.000 in the Blizzard NXT) uses a 3-LED fault indicator sequence to communicate error codes without a display. Coleman Mach Heat Ready boards (part 8330B3851) use a single LED blink pattern. Board lockouts most commonly result from three conditions: reversing valve non-response (fault code 3 on Dometic, 4-blink on Coleman), defrost cycle timeout when an outdoor coil thermistor reads out of range, or a low-pressure switch trip when refrigerant charge has dropped. Many lockout conditions are recoverable by removing 12V control power for 30 seconds to clear board memory - but if the underlying cause is not fixed, the board will re-lock within one heating cycle. Our technicians carry both Dometic and Coleman replacement boards as truck stock during the October through March heating season, when Florida nights drop into the 40s and these calls spike. We always verify the root-cause fault before clearing a board lockout to avoid a same-week callback.
Heat Pump Efficiency Loss From Dirty Coils and Low Refrigerant Charge
An RV heat pump operating with partially blocked evaporator coils or a marginal refrigerant charge will still run - it just won't hit rated capacity. Dometic Penguin II heat pumps carry a 13,500 BTU cooling / 10,500 BTU heating rating. A coil blocked 30% by dust, lint, and debris typically reduces effective output by 15-22% based on static pressure measurements we take at the return and supply plenums. In heating mode, that translates to supply-vent air that measures 74-78 degrees F instead of the expected 84-90 degree F range at 50-degree outdoor ambient. Refrigerant charge loss is less common in RV units (the systems are hermetically sealed at the factory) but does occur at flared fittings that loosen over time or after any work involving refrigerant lines. Florida requires EPA 608 certification for refrigerant handling - our technicians hold that certification and carry R-410A and R-22 recovery equipment. Low-charge diagnosis starts with suction-line temperature measurement (should be 15-20 degrees F above outdoor ambient in heating mode) before any refrigerant handling, since most low charge calls turn out to be airflow issues curable with a coil cleaning and gasket reseal at a fraction of the cost.
Also see: AC & Heating Services
This page covers heat pump service specifically. For the full range of ac & heating services we offer, visit our AC & Heating service overview.
Case Study: Dometic Penguin II heat pump reversing valve solenoid coil (part 3312771.025) failed open - the valve stuck in cooling position regardless of thermostat mode, and the defrost control board (part 3312564.000) showed an error lockout preventing restart
RV: 2019 Keystone Montana 3855BR • Location: Sun N Fun RV Resort, Site 33 • City: Sarasota
Symptom: Heat pump blew room-temperature air in heating mode - indoor air measured 68 degrees F at the supply vent while outdoor temp was 52 degrees F, and the unit cycled off after 4 minutes without the compressor ever reaching full speed
Diagnosis: Technician measured solenoid coil resistance at 487 ohms against the spec of 85-120 ohms, confirming open-circuit failure. Suction-line temperature in heating mode read 41 degrees F rather than the expected 55-65 degree F range, consistent with the valve staying in cooling position. Defrost board pulled fault code 3 (reversing valve not responding).
- Voltage and Amperage Baseline: Measured incoming voltage at unit junction box - 118.4 VAC on a 30-amp pedestal. Clamp-metered compressor amp draw at startup: 14.2A running vs. 18A nameplate, indicating compressor not reaching full load due to valve fault.
- Reversing Valve Solenoid Test: Disconnected the solenoid coil leads and measured coil resistance with a Fluke 117 multimeter - reading was 487 ohms vs. the 85-120 ohm spec in the Dometic Penguin II service manual. Confirmed open-circuit solenoid coil failure.
- Defrost Board Fault Code Pull: Accessed the defrost control board (Dometic 3312564.000) via the evaporator compartment cover. Board displayed fault code 3 on the LED indicator sequence, indicating reversing valve non-response lockout. Cleared board memory by removing 12V control power for 30 seconds.
- Reversing Valve Solenoid Replacement: Sourced replacement solenoid coil (Dometic 3312771.025) from truck stock. Removed the two coil-mounting screws on the valve body, slid old coil off the valve stem, and seated the new coil. Torqued mounting screws to 18 in-lb. Did not disturb refrigerant lines.
- Heating Mode Verification: Set thermostat to heat mode at 75 degrees F. Monitored suction-line temperature with a contact thermometer - rose to 61 degrees F within 3 minutes, confirming valve now fully reversing. Supply vent measured 84 degrees F at 8-minute steady-state operation.
- Defrost Cycle Test: Manually triggered defrost cycle via the board test jumper. Unit shifted to defrost, outdoor fan stopped, indoor fan continued - cycle completed in 4 minutes 22 seconds and unit returned to heat mode without fault code.
- Final Amp Draw and Documentation: Verified compressor amp draw at 17.8A in heating mode - within nameplate spec. Documented all readings on the service ticket and walked owner through the new defrost board fault code chart taped inside the unit access panel.
Outcome: Heat pump restored to full heating and cooling operation in a single 2.5-hour visit. Owner confirmed supply-vent temps consistent across all three bedroom outlets before technician departed.
Time on-site: 2 hours 30 minutes • Total cost: $487 (service call + solenoid coil + defrost board reset) • Dealer alternative: $1,100-$1,400 estimated (dealer quoted full heat pump unit replacement without diagnosing the solenoid separately)
“I had no idea the heat pump could get stuck in cooling mode. The tech showed me the resistance reading on his meter and explained exactly what had failed. Fixed on the spot, no dealer trip, no waiting a week for an appointment.”
RV Heat Pump Unit Comparison - Common Florida Service Units
| Unit | Model Number | BTU Cooling / Heating | Refrigerant | Common Failure Part | Replacement Part Number |
|---|---|---|---|---|---|
| Dometic Penguin II HP | 641816C-XX.XX | 13,500 / 10,800 BTU | R-410A | Reversing valve solenoid coil | 3312771.025 |
| Coleman Mach Heat Ready | 47004-876 | 15,000 / 14,200 BTU | R-410A | Defrost control board | 8330B3851 |
| Dometic Blizzard NXT HP | 3314952.516 | 15,000 / 12,500 BTU | R-410A | Defrost board thermistor | 3313107.000 |
| Advent Air Heat Pump | ACM150HP | 15,000 / 12,000 BTU | R-410A | Reversing valve body (full) | ACMRVV-001 |
| Furrion Chill HP | FACR14SA-PS | 14,500 / 11,000 BTU | R-410A | Control board / inverter module | F2CPSH00A |
Signs You Need Heat Pump Service
- ✓Test reversing valve solenoid coil resistance (spec: 85-120 ohms on Dometic Penguin II; open circuit above 300 ohms confirms failure)
- ✓Pull defrost board fault codes before clearing any lockout - resets without root-cause fix cause same-week callbacks
- ✓Measure suction-line temperature in heating mode (expected: 15-20 degrees F above outdoor ambient; readings below ambient indicate valve stuck in cooling position)
- ✓Check return-air filter and evaporator coil for blockage - 30% coil restriction reduces heating output by up to 22%
- ✓Verify 12V control circuit voltage at solenoid coil terminals during mode switch (should see 11.8-13.2V DC during valve activation)
- ✓Document supply-vent temperature at steady state in both heating and cooling modes before signing off
Heat Pump Service - Pricing
Typical price range: $225 - $950
All calls start with a $299 service-call fee that covers the technician's trip to your location and the first hour of diagnosis. That $299 applies toward any repair you authorize - it is not an additional charge on top of the repair. Pricing shown is a national average range; your exact quote is provided in writing on-site before any work begins.
Heat Pump Service - Common Questions
Straight answers from our heat pump service service call log.
My heat pump cools fine in summer but blows cold air in heating mode - what part failed?
That's almost always the reversing valve solenoid coil. The valve itself redirects refrigerant flow between heating and cooling - when the coil fails open-circuit, the valve stays stuck in whatever mode it was last in. A $15 coil resistance test with a multimeter confirms it in under 5 minutes. The coil replacement (Dometic part 3312771.025 on Penguin II units) does not require touching refrigerant lines.
Can a heat pump replace my RV furnace entirely in Florida winters?
For most of Florida, yes - from Orlando south. Heat pumps lose efficiency below about 35 degrees F outdoor ambient, and most Florida nights stay above 40 degrees F from November through March. North Florida and Panhandle winters can push below 32 degrees F for days at a time, where you would want the propane furnace as a backup. The Coleman Mach 47004-876 has an electric strip heat backup that kicks in at low ambient temps, which covers most edge cases.
How do I know if my heat pump is low on refrigerant or just has dirty coils?
Suction-line temperature tells you. In heating mode, the suction line should read 15-20 degrees F above outdoor ambient temperature. If it is reading at or below outdoor ambient, you have a refrigerant or airflow problem. A dirty evaporator coil causes high suction-line superheat and restricted airflow at the supply vent. Low refrigerant causes low suction-line temperature and low amp draw on the compressor. Both are diagnosable without opening the refrigerant circuit.
What does fault code 3 mean on a Dometic Penguin II heat pump board?
Fault code 3 on the Dometic defrost control board (3312564.000) means the board attempted to activate the reversing valve and got no confirming response from the valve position sensor within the timeout window. Most commonly caused by a failed solenoid coil (open circuit) or a valve mechanically stuck from debris. Clearing the board by removing 12V control power for 30 seconds resets the lockout, but the fault returns immediately if the valve has not been repaired.
Is a heat pump service call worth it or should I just replace the whole unit?
Depends on the failure. Solenoid coil replacement runs $280-$390 on-site and restores a unit to full operation. Defrost board replacement is $190-$310. Full unit replacement (Dometic Penguin II HP installed) runs $1,350-$1,650 on-site. If the compressor itself has failed, replacement is the right call. If it is a valve, board, or coil failure, a repair costs 20-30% of a new unit and typically runs 3-5 more years in Florida conditions.
How long does a heat pump service call take?
A reversing valve solenoid replacement takes about 2 to 2.5 hours on-site including diagnosis, repair, and heating/cooling cycle verification. A defrost board swap takes 90 minutes. If a refrigerant recharge is needed (EPA 608 required), add 45 minutes for recovery, vacuum, and recharge to spec. We carry R-410A on the truck and can complete most heat pump service calls in a single visit.
More AC & Heating Services
Other specialized repairs under ac & heating - all done at your location, no tow required.
Where We Provide Heat Pump Service in Florida
Coast to Coast RV Repair runs heat pump service jobs across these cities. Click your closest one for local-specific info, response times, and campground coverage.