A/C Evaporator Housing - Water Leaks to Interior
Article No. 85-11-16AIR CONDITIONING - INADEQUATE DRAINAGE FROM EVAPORATOR HOUSING
LIGHT TRUCK 1975-85 ECONOLINE
During conditions of high humidity and high blower operation, evaporator condensate leaks into the passenger compartment from the A/C blower housing, blower housing to evaporator housing flange and/or the A/C register outlets.
The fundamental cause of this leakage is that the blower is located downstream of the evaporator core (draw through system), resulting in a negative housing pressure with respect to ambient. During this condition of negative pressure, air flow can be drawn through the drain tube into the housing opposing the flow of condensate drainage out of the drain tube. Also, air leakage into the housing because of insufficient drain tube sealing can cause this concern.
Due to improper condensate drainage, water can accumulate in the bottom of the temperature blend door frame assembly and spill into the blower housing. If this condition occurs, insufficient sealing at the blower housing to evaporator housing flange and at the blower scroll cover to blower housing may allow leakage into the passenger compartment from these areas.
An accumulation of water in the blower housing may result in water being blown through the register ducts and register outlets.
PROCEDURE:
Install the new check valve drain tube assembly which completely shuts off air flow through the drain tube, due to the negative pressure, yet allows water to drain freely under all housing negative pressures encountered in service.
Due to manufacturing variations of evaporator assemblies, some units are more susceptible to condensate accumulation and will require rework of the blend door frame and may necessitate resealing the lower housing flange.
The following three drain tube systems may be reworked as outlined in the following paragraphs.
Figure 18:
Econoline Vehicles with (Production) Aspirator Drain Tube Built March 1984 through September 1984
Drain Tube Replacement (Refer to Figure 18)
1. Pull the aspirator air hose from the aspirator outlet drain tube assembly.
2. Remove the aspirator outlet drain tube assembly from the barbed connection of the plastic evaporator drain tube projecting inboard from the bottom of the housing.
3. Remove the plastic evaporator drain tube and seal attached to the bottom of the evaporator housing by removing the two attaching screws with a 5/16 inch socket. Inspect the plastic drain tube for cracks or chips from the barbs which would provide an air leak path. Inspect the seal for full sealing contact around the drain opening from the housing to the drain tube. If not properly sealed, replace seal or apply silicone sealer to the seal surface to insure a complete seal. Install seal, drain tube and attaching screws.
4. Plug aspirator air hose with rubber cap 382443-S or similar and tape hose out of the way on the underside of evaporator housing.
5. Install the new check valve drain tube assembly, E5UZ-19858-B, to the barbed end of the plastic drain tube projecting from the underside of the evaporator housing with the check valve down.
Blend Door Frame Rework and Resealing of Lower Housing Flanges
The plastic blend door frame assembly introduced to production in March 1984, requires the addition of drain holes to prevent the accumulation of water. Add holes as follows:
Figure 19:
1. Remove the blower motor and resistor connections from the blower scroll cover (Figure 19).
2. Remove blower scroll cover (7 screws) and blower motor (4 screws) from blower housing (push/pull blower motor wire grommet toward inside of evaporator housing) (Figure 19).
Figure 20:
3. Drill two 3/16 inch holes approximately 30~ downward at locations shown in Figure 20. Exercise caution when breaking through to prevent drilling holes through bottom of evaporator housing.
Figure 21 - BLOWER HOUSING FLANGE AND DOOR SHAFT SEALING:
4. Check the lower flange of the blower housing to evaporator housing (Figure 21) for leaks by plugging drain tube and pouring a quantity of warm water into the blend door frame, through the blower motor opening, until the water level is approximately 3/8 inch deep. If leakage is noted, drain housing and proceed to the next step. Otherwise, remove plug from drain tube, drain housing and proceed to Step 8.
5. If leakage was noted from the bottom end of the OUTSIDE-RECIRC door shaft, blow compressed air around the end of the shaft area until thoroughly dry. Apply black silicone sealer, D6AZ-19562-A, liberally and completely over the end of the shaft and boss to seal the area to the housing (Figure 21).
6. If leakage was noted from the flange, remove 8 screws from the bottom and sides of the housing flange (2 screws inside blower housing). Leave the top 3 screws in place as well as the vacuum actuator shaft clip.
Figure 21 - BLOWER HOUSING FLANGE AND DOOR SHAFT SEALING:
7. Pry the flange apart between the blend door frame and evaporator housing, and the flange between the blower housing and blend door housing/evaporator housing. Thoroughly blow dry the sealing areas with compressed air. Apply a continuous bead of black silicone rubber sealer on the sealing surfaces across the bottom flange and 1-1/2 inches up the sides of the three parts (Figure 21). Carefully place flanges together and reassemble 8 screws. Allow time for sealer to set up and repeat leak test of Step 4.
8. Check temperature blend door for full travel and adjust if necessary as described in the applicable shop manual.
9. Inspect blower scroll cover seal for full contact impression with edge of blower housing. If full contact is not evident or seal is damaged, replace seal or repair skip areas with silicone sealer.
10. Reassemble blower, blower scroll, and electrical connections and check for proper blower operation as described in the applicable shop manual. Be sure blower motor wire grommet is pulled into hole in housing.
Figure 22 - "DUCK BILL" EVAPORATOR DRAIN TUBE-REMOVAL:
Econoline Vehicles with "Duck Bill" Drain Tube Built Prior to March 1984
"Duck Bill" Drain Tube Replacement
1. Remove the original drain tube located in the engine compartment on the bottom of the evaporator housing - two screws (Figure 22).
Figure 23 EVAPORATOR DRAIN TUBE INSTALLATION-ECONOLINE:
2. Install the new check valve and drain tube assembly and retainer (service kit D6UZ-19858-B) using the two hex head 5/8 inch long, No. 10 screws provided (Figure23). Note that the key tab fits into the slot towards the front of the vehicle. Two spring nuts are available in the kit, if required.
3. Apply a liberal bead or fillet of silicone sealer to both sides of the sealing surfaces to seal any air leak paths due to housing surface irregularities.
Procedure for Inspection and Repair of Evaporator/ Blower Housing Flange and Cover Leaks into Passenger Compartment
Figure 19:
1. If equipped with an EEC IV system module in front of blower housing, remove module cover and dash flange attaching screws and lay module aside (Figure 19).
2. Check the lower flange of the blower housing to evaporator housing seal and the OUTSIDE-RECIRC door shaft lower pivot for leaks by plugging the drain tube and placing the FUNCTION lever in MAX A/C. Then, pour a sufficient quantity of warm water through the RECIRC door opening until the water level is approximately 3/8 inch deep. If leakage is noted, drain housing and proceed to the next step. Otherwise, remove plug from drain tube, drain housing and proceed to Step 6.
Figure 21 - BLOWER HOUSING FLANGE AND DOOR SHAFT SEALING:
3. If leakage was noted from the bottom end of the OUTSIDE-RECIRC door shaft, blow compressed air around the end of the shaft area until thoroughly dry. Apply black silicone sealer, D6AZ-19562-A, liberally to cover completely the end of the shaft and boss to seal the area to the housing (Figure 21).
4. If leakage was noted from the flange, remove the blower motor resistor connections and the blower housing motor cover (Figure 19). Remove 8 screws from the bottom and sides of the housing flange (2 screws inside blower housing). Leave the top 3 screws in place, as well as the vacuum actuator shaft clip (Figure 21).
Figure 21 - BLOWER HOUSING FLANGE AND DOOR SHAFT SEALING:
5. Pry the lower flanges of the blower and evaporator housing apart. Thoroughly blow dry the sealing areas with compressed air. Apply a continuous bead of black silicone rubber sealer on the sealing surfaces across the bottom flange and 1-1/2 inches up both sides (Figure 21). Carefully place flanges together and reassemble 8 screws. Allow time for the sealer to set up and repeat leak test of Step 2.
6. Remove blower scroll cover and inspect blower housing cover seal for full contact impression with edge of blower housing. If full contact is not evident or seal is damaged, replace seal or repair skip areas with silicone sealer.
7. Reassemble blower scroll cover and electrical connections, and EEC IV system module (if so equipped).
8. Check for proper blower operation as described in the applicable shop manual.
Econoline Vehicles Built from 1975 through February 1984 Serviced with Aspirator Drain Tube Kit Per TSB 84-18-21-S
Figure 24 - SERVICE ONLY CHECK VALVE DRAIN TUBE ASSEMBLY - INSTALLATION:
Drain Tube Replacement (Refer to Figure 24)
1. Pull the aspirator air hose from the aspirator drain tube.
2. Plug the aspirator air hose with rubber cap 382- 443-S or similar, and tape hose out of the way on the underside of the housing.
3. Remove the drain hose located in the engine compartment on the bottom of the evaporator housing - two screws.
4. Install the new check valve and drain tube assembly and retainer (service kit D6UZ-19858-B) using the two hex head 5/8 inch long, No. 10 screws provided. Note that the key tab fits into the slot towards the front of the vehicle. Two spring nuts are available in the kit, if required.
5. Apply a liberal bead or fillet of silicone sealer to both sides of the sealing surfaces to seal any air leak paths due to housing surface irregularities.
6. To inspect the passenger compartment for leaks and/or repair the evaporator/blower housing flange cover seals, refer to the procedures described after the "Duck Bill" drain tube replacement procedures.
PART NUMBER PART NAME CLASS
E5UZ-19858-B Check Valve Assy. A
Production Aspirator Drain Tube Built March 1984 thru Sept. 1984
D6UZ-19858-B Check Valve Assy. B
Duck Bill Drain Tube Built Prior to March 1984
D6UZ-19858-B Check Valve Assy. B
Service Only Aspirator
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP19858A85 Vehicles Produced from 1975-84 (Produced prior to September 1984)
TIME: 1.2 Hrs.
OPERATION: SP19858A85 Vehicles Produced from 9/84 to Date
TIME: 1.5 Hrs.
DLR CODING: Basic Part No. 19858 - Code: 48