A York light-commercial rooftop is a packaged unit: compressors, condenser, evaporator, blower and gas heat section in one cabinet sitting on a roof curb. The platform this page covers is the Predator family, sold under the series letters ZF, ZH, ZJ and ZR in sizes from 3 to 12.5 tons, along with the older Sunline units still running on plenty of roofs. York's residential furnaces and air conditioners are a separate subject, covered on our York furnace and AC page.
A Predator is run by a Simplicity unit control board, and that board keeps a memory. Its status LED beats one second on, one second off in normal operation, and a fault shows as a count of fast flashes. The board stores the last five alarms, which a technician recalls with the LAST ERROR button, and we read that history first, because a unit that tripped at 3 a.m. and restarted on its own looks healthy by the time anyone climbs the ladder.
York is the brand Johnson Controls built the Predator platform under. In 2024 Johnson Controls announced the sale of its residential and light-commercial HVAC business to Bosch, so paperwork on newer equipment may carry a different corporate name. The unit on your roof, its model number and its part numbers are unchanged by that.
Before you book, read the lease. Commercial leases differ on who pays for rooftop maintenance, repair and replacement, and the tenant who makes the call is not always the party who signs the invoice. We write up what failed, what it needs and whether the unit is worth the money, so that whoever is responsible can act on one document.
York rooftop units lines we install and service
R-410A packaged rooftops from 3 to 12.5 tons, built as gas/electric units or as cooling units with optional electric heat. The larger frames carry two compressors on separate circuits, which is why one side can lock out while the unit keeps half its cooling. Each compressor circuit has its own high-pressure, low-pressure and freezestat alarm on the control board.
The generation before Predator, still heating and cooling older plazas and light-industrial units. We service them, but a failed heat exchanger or compressor on a Sunline is usually the point where replacement is the better money. A changeout raises the curb question: the new cabinet must match the existing roof curb or sit on a curb adapter.
Predator units use Simplicity boards that report by flash code. Newer York rooftops use Smart Equipment controls, which show faults as text on a display at the board. Either way the control keeps a record, and a thermostat that reports only a trouble light is telling you to go and read it.
A draft (inducer) motor, an ignition control with its own flash codes, a flame sensor, rollout and limit switches, and a tubular heat exchanger. It sits unused in a wet cabinet all summer and is asked to light on the first cold morning in October. That is when it fails.
The damper package that brings in outdoor air for ventilation and for free cooling on mild days. Its actuator, sensors and linkage are the most neglected parts on the roof. Our RTU economizer repair page covers what a stuck damper costs you in gas and hydro.
What goes wrong on York rooftop units equipment
No heat on the first cold morning: gas heat section
The blower runs and the air is cold. On a Predator, nine fast flashes on the unit control board mean the ignition control has locked out or failed. The cause is one of four parts: a seized draft motor, a failed ignition control, a fouled flame sensor or a tripped rollout switch. A tripped rollout is never a reset-and-leave item: it means flame left the burner box, and we find out why before the unit fires again.
Economizer damper actuator stuck open or closed
Stuck open in January, the damper pours outdoor air across the heat exchanger: the space never warms, the gas bill climbs and the people near the diffusers complain first. Stuck closed, the building loses its ventilation air and the compressors run on mild days when outdoor air would have cooled the space for free. We stroke the actuator, check the linkage and test the sensors before replacing anything.
Worn blower belts and bearings on belt-drive models
A belt that squeals at start-up, a rumble from the blower section or airflow that fades over a season. A slipping belt cuts airflow, and low airflow freezes the evaporator in summer and trips the high limit in winter, so the complaint often arrives as a cooling or heating fault. Belts are a maintenance item; a blower bearing left to fail takes the shaft with it.
Compressor lockouts on pressure or freeze protection
Three to six flashes on the Predator board are high-pressure and low-pressure lockouts on compressor circuits one and two, and seven or eight are freezestat trips. High pressure usually means a matted condenser coil or a dead condenser fan motor. Low pressure and freezestat trips mean dirty filters, a slipping belt or a refrigerant leak. Refrigerant work requires an ODP card, and we find the leak before adding charge.
York rooftop units warranty: what to know
- Commercial warranty terms are set by the model, the options ordered and the start-up date, not by a single published residential term. Have the model and serial number from the unit nameplate ready and we will check it with the distributor.
- Compressors and heat exchangers generally carry longer coverage than the other parts on a commercial unit. Confirm the actual years against the serial number before anyone orders a major component.
- A parts warranty supplies the part. Labour, refrigerant, crane time and after-hours access are billed, so a covered compressor is still a real invoice.
- Keep the start-up sheet and the maintenance log. A unit with no filter, belt or coil-cleaning record is harder to claim on, and the log is also what a buyer or a new tenant will ask to see.
- ZK Mechanical services York as an independent contractor. Warranty parts are claimed through the York parts distributor against the serial number, whoever installed the unit.
Parts availability in the GTA
York commercial parts move through the manufacturer's Source 1 parts channel and its distributors, and universal items cover a good share of rooftop repairs. Belts, filters, contactors, capacitors, flame sensors and igniters are common stock, while draft motors, ignition controls, Simplicity boards, economizer actuators and compressors are ordered by model and serial number. There is no published price band for commercial rooftop repairs, because the bill depends on the part, the tonnage, roof access and whether refrigerant has to be recovered, so every job gets a written quote before work starts. We confirm availability first: a store with no heat needs to know on day one whether the part is across town or a week away.
Common questions
Who is licensed to repair the gas heat on a York rooftop unit in Ontario?
A TSSA-certified gas technician whose licence class covers the unit's input rating. A G2 covers appliances up to 400,000 BTU/h, which takes in most light-commercial rooftop heat sections; anything larger needs a G1. Refrigerant work on the cooling side separately requires an ODP card. Ask for both before anyone opens the cabinet, and expect the technician's licence number on the invoice.
My York rooftop reset itself and is running again. Does it still need service?
Yes, if it tripped more than once. The Simplicity board keeps its last five alarms, so the reason for an overnight lockout can be read days later. A unit that keeps resetting on a pressure switch or an ignition fault is working its compressors or its heat section harder each time. Reading the history is a short visit; replacing a compressor is not.
Can an old York Sunline be replaced with a different brand?
Yes. The new unit sits on the existing roof curb through a curb adapter matched to both footprints. The job may also need a crane lift, a gas and electrical reconnection, a building permit from the municipality and an ESA notification for the electrical work. Our commercial RTU replacement guide walks a property manager through the sequence.
How often should a York rooftop unit be serviced?
Twice a year at minimum: before cooling season and before heating season. Filters and belts on a busy retail or restaurant unit need attention more often than that. Each visit should cover the coils, the drain, the economizer, the burners and the stored alarm history. A commercial maintenance contract puts those visits on a schedule so the first cold morning is not the test.
What does a York RTU repair cost?
It depends on four things: the part, the unit's tonnage, how the roof is reached and whether refrigerant must be recovered and recharged. A flame sensor or a belt is a small bill; a compressor or a heat exchanger on a 10-ton unit is a decision about replacement. We quote in writing before work starts. For budgeting a new unit, see what a commercial rooftop unit costs.