The outdoor condenser for a central air or heat pump system is one of the quieter items on a Creve Coeur roof job, and one of the easiest to overlook when the crew starts planning. It usually sits on a pad at the side or back of the house, often under or near the eave, and the roof work happens directly above it. Before you agree to a start date, it helps to know what the crew will need from that corner of the lot and who needs to be there when they get it.
Where the roof work lands on the unit
Tear-off debris falls straight down the slope, and in a typical job the old shingles go into a dumpster or a trailer staged close to the house. A condenser under the eave can end up in that drop zone even when the dumpster sits at the drive. Nails, granules and small pieces of underlayment can get into the fan grille and onto the coil fins. Those fins are thin, and bent fins restrict airflow, which is one reason homeowners sometimes see cooling output drop for a season after a roof job they assumed was harmless.
Ask the roofer to show, on a plan or on a walk, which part of the eave overhangs the unit. Then ask how the crew will cover it during tear-off. A tarp or a plywood cover is common, but the cover should not sit tight against the fan grille, and it should come off at the end of each working day so air can still move through the coil.
Clearance the crew needs, and clearance the unit needs
The condenser needs open space for air to move through the coil. Manufacturers publish minimum clearances on the unit's data plate and in the installation manual, and those numbers are the ones to check, not a rule of thumb from a neighbor. A service tech can confirm them when you ask. The crew's needs are separate: they need a route to the eave and a place to set a ladder that does not put weight on the cabinet. A ladder resting on or leaning against an AC cabinet can dent the top panel and crack a fan guard, and a dented cabinet is a conversation you would rather not have with your HVAC company later.
Put the ladder placement in writing. Ask the roofer where each ladder will stand on the side of the house with the condenser, and ask whether the crew will use a stand-off or a ladder stabilizer that spreads the load onto the wall rather than the unit. This is one place where a written answer is worth more than a promise made in the driveway.
The disconnect, and who shuts the power off
Most condensers have a disconnect box mounted on the wall near the unit, and the unit is wired through it. Roofers do not work on that wiring, and they should not be the ones to switch the system off or back on. Ask the HVAC company who will turn the system off before tear-off begins and who will turn it back on when the new roof is finished. If the answer is not clear, the unit may be left running with debris coming at it, or it may be left off through a hot week with nobody checking.
Summer is the case that matters most. St. Louis summer afternoons can run hot and humid, and a house without its condenser running for a day or two in July is a different problem from the same gap in April. If your roof job falls in a hot stretch, decide with the HVAC company in advance whether the system will stay off during the working day, and who will confirm it is running again at the end of it.
Line set, drain and the wall behind the unit
The copper line set runs from the condenser to the indoor coil, and it is insulated where it runs along the wall. Roof work near that wall can pinch the insulation, pull on a line during a ladder move, or bump the drain line that carries condensation away from the indoor unit. None of these are common, but each one is a quick repair when caught early and a much longer conversation when found weeks later. Ask the HVAC tech to note the condition of the line set and the drain before the roof crew arrives, and photograph both.
The wall behind the unit also matters at the flashing where the roof meets the house. If the new roof work runs close to the wall above the unit, the flashing crew and the HVAC tech should agree on where the line set exits the wall. A penetration there should stay sealed when the roof is done, and checking that seal belongs in the final walkthrough, not in a note added after the crew has left.
What to put in the roof bid
A roof bid should name the condenser, not just the house. The useful lines are simple. The bid should say whether the crew will cover the unit during tear-off, whether they will keep ladders off the cabinet, and where the dumpster and trailer will be staged relative to the unit. It should also say who is responsible for the cover and whether the cover comes off at the end of each day. If the bid says nothing on these points, ask for the answers in writing before you sign.
Keys Roofing documents the condition of the outdoor unit in the job photo set before work begins, and the written scope lists the areas the crew will protect. Those photos and that scope stay in your hands. The HVAC company is a separate contractor, and it is the one to confirm the condenser clearance, the disconnect and the condition of the line set. If you want the cover or its removal priced, ask for it as its own line in the bid rather than a general protection charge.
Questions to ask before the crew books
- Which side of the house does the condenser sit on, and does the eave overhang it?
- Who turns the system off before tear-off, and who turns it back on after the final walk?
- Where will each ladder stand, and will any ladder rest on the cabinet?
- Will the unit be covered during tear-off, and when is the cover removed each day?
- Where will the dumpster and trailer stage relative to the unit?
- Who checks the line set, the drain and the wall penetration before and after the job?
If you are not sure who to call, the Keys office at (314) 220-2333 can tell you what the crew plans for the side of the house with the unit. Ask the HVAC company the questions on this list at the same time, so the two answers match before the roof truck arrives.