Most likley it's the drain tube that carries the condensation ouy of the ductwork. Look at the bottom of the A/C evap case, find and clear the drain tube. Here is a Tech bulletin about this tube and possible problems caused by it.
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE
TECHNICAL SERVICE BULLETIN
Reference Number(s): NTB99-006, Date of Issue: March 15, 1999
Related Ref Number(s): NTB99-006
1998-99 ALTIMA, MIL 'ON' AND/OR POOR DRIVEABILITY DUE TO
A/C EVAPORATOR CONDENSATION LEAKING ON ECM
Model(s): 1998-99 Nissan Altima
Section: Heater & Air Conditioner
Bulletin No: NTB99-006
Date: March 15, 1999
All 1998-99 Nissan Altima (L30)
If a 1998-99 Nissan Altima exhibits a MIL 'ON' and/or poor driveability such as
engine hesitation or no starting, the cause may be air conditioning (A/C) evaporator
condensation leaking onto the engine control module (ECM). Air conditioning
condensation can accumulate and leak onto the ECM if the A/C evaporator drain
tube becomes blocked by debris such as leaves, insect nests, etc.
Such debris can enter the A/C air intake duct through openings in the cowl top
cover. To prevent debris from entering the A/C system, new cowl top covers are
now available. The new cowl top covers have foam seals (mounted on their
underside) that keep debris away from the A/C air intake duct.
Check for moisture and/or mildew on the passenger side carpeting around the
ECM area and check the ECM for signs of water damage, See Fig. 2 CM
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE. Page 1 of 6
If the carpeting is dry and mildew-free around the area of the ECM and
there are no signs of water damage (wetness, water spots, corrosion, etc.)
to the ECM, use the service manual to diagnose the incident DTCs.
If the carpeting is wet and/or mildew is present around the ECM and the
ECM has signs of water damage (wetness, water spots, corrosion, etc.),
proceed with step 2.
Discharge the A/C system using the procedure on pages HA-61 and HA-62 of
the 1998 Altima Service Manual or pages HA-62 and HA-63 of the 1999
Altima Service Manual.
Remove the A/3. C evaporator assembly.
CAUTION: Immediately after removing the evaporator assembly,
seal the open ends of the refrigerant lines (both on the
evaporator and on the vehicle) to prevent moisture
from entering the A/C system.
Using a wet/dry vacuum cleaner, remove all debris inside the evaporator
including any debris that may be blocking the drain tube. Make sure the drain
tube is free and clear of any debris and flashing that was created when the
evaporator case was initially manufactured.
Using a wet/dry vacuum cleaner remove all debris inside the intake blower
unit. Remove the intake blower unit if necessary.
6. Dry the carpeting using the following steps.
With a large towel, soak up as much water as possible from the top
surface of the carpet.
Pull back the wet sections of the carpet until the underside of the wet
section is exposed.
Using a wet/dry vacuum cleaner, remove as much water as possible from
the underside of the carpet.
Spray the wet areas of the carpet with a household disinfectant to
eliminate mold or mildew odors and prevent further growth.
E. Allow the carpet to dry.
NOTE: Use a fan to shorten the drying time.
7. Install the new cowl top covers as follows:
A. Remove the windshield wiper arms (two M10 nuts).
B. Remove the weather-strip seal, Fig. 1
Remove and discard the old cowl top covers. Save the two securing clips,
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE. Using a wet/dry vacuum cleaner, remove all debris in the cowl and A/C
Install E. The new cowl top covers.
F. Re-install the weather-strip seal.
8. Reinstall the windshield wiper arms and the attachment nuts.
IMPORTANT: When re-installing the wiper arms, use the
procedure on page EL-110 of the 1998 Altima
Service Manual or page EL-116 of the 1999 Altima
Service Manual to properly position the wiper arms.
Once correctly positioned, tighten the wiper arm
mounting nuts to 17-23 N-m (1.7-2.3 kg-m, 12-17 ftlb).
9. Reinstall the A/C evaporator assembly.
NOTE: When installing the evaporator assembly, make sure
the drain tube is correctly positioned and the
carpeting/insulation does not get caught between the
drain tube foam seal and the engine room wall.
Replace the water damaged ECM with the correct service part number. See
Evacuate and recharge the A/C system with 0.70-0.80 kg (1.54-1.76 Ib) of
Conduct a leak check to confirm there are no refrigerant leaks. Refer to the leak
check procedure on pages HA-58 through HA-60 of the 1998 Altima Service
Manual or pages HA-59 through HA-61 of the 1999 Altima Service Manual.
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE. Fig. 1: Removal of Old Cowl Top Covers
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE. Fig. 2: Location of ECM
Description Part Number Quantity
Cowl Top Cover (RH) 66862-0Z000 1
Cowl Top Cover (LH) 66863-0Z000 1
ECM - Fed, M/T (1998-
ECM - Fed, A/T (1998-
ECM - Cal, M/T (1998-
MIL ON/POOR DRIVEABILITY - A/C EVAPORATOR CONDENSATE. Description Part Number Quantity
ECM - Cal, A/T (1998-99
Submit a Primary Failed Part (PP) line using the following claims coding:
Description PFP OP CODE SYM DIA FRT
Replace cowl panel 66862-
UE24AA (1) 57 0.2 hrs.
--- TB777A --- --- 0.6 hrs.
Replace ECM (if
--- DE28AA --- --- 0.5 hrs.
(1) As indicated by customer complaint.
Sunday, July 17th, 2011 AT 4:46 PM