Acura CL (1G) Clogged Evaporator Drain Cleaning
Introduction
On the first-generation Acura CL, condensation from the air-conditioning evaporator is supposed to drain out under the car through a hose and spigot in the passenger-side HVAC housing. When that drain clogs, water backs up inside the evaporator case and spills into the passenger footwell instead of dripping onto the ground. Owners typically notice this in humid weather: the carpet gets wet, water sloshes into view during hard left turns or under acceleration, and little or no condensate is seen beneath the car. Because the trapped water sits near the ECU, clearing the drain promptly protects the electronics as well as the interior. This guide covers accessing the housing, optionally refreshing the seal between the blower and evaporator, and flushing the drain without discharging the air-conditioning system. Adapted from a community writeup by Tehvine on AcuraZine (https://acurazine.com/forums/1g-cl-diy-faq-74/diy-leaky-evap-box-clogged-drain-495059/), including corrections from the follow-up discussion.
Reference
Tools Required
- Ratchet and socket set
- Phillips screwdriver
- Compressed air source (compressor or canned air)
- Shop vacuum
- Zip tie (used as a drain probe)
- Plastic sheeting or shop towels
Parts Required
-
Adhesive-backed foam rubber seal (optional, to refresh the blower-to-evaporator joint)
Safety Warnings
- ⚠ Standing condensate can reach and damage the ECU in the passenger footwell, so clear the drain before water accumulates.
- ⚠ Do not spread the housing open more than about 1/3 inch; the plastic case cracks easily.
- ⚠ Fully removing the evaporator case requires discharging the A/C system, which must be handled by someone equipped to recover refrigerant. Do not open sealed refrigerant lines yourself.
Step-by-Step Instructions
1 Confirm the symptom
Water pooling on the passenger floor, especially when it surges into view during hard left turns or under acceleration, together with little or no condensate dripping beneath the car, points to a blocked evaporator drain rather than a body leak. Because the standing water can reach the ECU in the footwell, treat this as worth addressing promptly.
2 Gain access on the passenger side
Work in the passenger footwell. Take out the glove box, then pull the door sill trim and the kick panel. Finally unbolt the silver structural brace that the glove box mounts to. Removing that brace opens up enough room to reach the HVAC housing.
3 Identify the evaporator housing and blower
The large case on the left holds the evaporator core where condensation collects; the black unit beside it on the right is the blower assembly. Confirm which is which before removing any fasteners so you work on the correct box.
4 Refresh the blower-to-evaporator seal (optional)
If the original foam gasket between the blower and the evaporator has aged and compressed, add fresh foam rubber to restore a tight seal at that joint. This step is preventive rather than required: a good seal keeps any future overflow from escaping onto the carpet and ECU instead of staying contained.
5 Loosen the lower half of the housing
Remove the roughly ten screws and bolts distributed around the evaporator case so its lower half can separate. Spread the bottom gently, no more than about 1/3 inch, because forcing it wider will crack the plastic. Note that completely removing the case requires evacuating the A/C refrigerant, which is beyond this cleaning procedure and is not covered here.
6 Disconnect and clear the drain
Lay down plastic or stage the shop vacuum first, since water can gush out. Slide the rubber hose off the drain spigot. If the blockage sits in the hose, blow it clear with compressed air and follow with the vacuum. If the drain pipe itself is plugged, which is the more common case, feed a zip tie up into the drain to break the clog loose and expect a sudden rush of water once it releases.
7 Drain fully, re-clear, and reassemble
Let the housing empty completely into the vacuum or a catch basin; if a large volume starts flowing before you are ready, reconnect the hose briefly to control it. Once drained, disconnect again and give both the hose and the drain a final pass with compressed air and suction to clear any remaining slime. Reattach the drain hose, then reinstall the brace, kick panel, sill trim, and glove box, and wipe up any spilled water.
Pro Tips
- 💡 Have the shop vacuum running and positioned before pulling the drain hose; the release can be sudden and heavy.
- 💡 Reconnect the drain hose promptly if water starts flowing faster than you can catch it, especially after driving on a humid day.
- 💡 While you have access, inspect the base of the evaporator case for accumulated grime and slime, which is usually what caused the blockage.
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