Air Conditioning - Poor Performance
Article No.94-2-9
01/26/94
AIR CONDITIONING - HIGH DISCHARGE TEMPERATURES - POOR A/C PERFORMANCE - VEHICLES BUILT FROM JOB 1 1989 TO 11/30/92
FORD:
1989-93 THUNDERBIRD
LINCOLN-MERCURY:
1989-93 COUGAR
ISSUE:
Poor A/C performance, high discharge temperatures, may be the result of incorrect welding of the temperature blend door. If this occurs, air flow from the evaporator will be allowed to leak through the heater core and poor A/C performance will result.
ACTION:
If the A/C system seems to be operating, but is not cooling the car properly, the temperature blend door frame could be incorrectly positioned. Follow the attached service procedure to position the blend door properly.
NOTE:
DO NOT PERFORM THIS PROCEDURE IF TSB 94-2-12 HAS BEEN PERFORMED. FOLLOW NORMAL DIAGNOSTICS FOR POOR A/C PERFORMANCE.
Verify the condition by performing the following diagnosis:
1. Run the A/C with the control set at MAX A/C and the blower on high for 5 minutes. Record the discharge air temperature at the center instrument panel register.
2. Clamp off the heater core hoses and continue to operate the system at MAX A/C with high blower for 10 minutes to cool the heater core.
3. Continue to operate the system on MAX A/C and high blower and record the discharge air temperature at the center instrument panel register. If there is a decrease in temperature of 5~F. (3~ C.) from the original temperature check made in Step 1, there is a good chance of an incorrectly welded door frame.
INCORRECTLY WELDED DOOR FRAME SERVICE PROCEDURE
Correct the condition by performing the following repair:
1. Remove the evaporator case from the vehicle. Refer to the 1993 Thunderbird/Cougar Service Manual, page 12-03-23, for the removal procedure.
2. Remove the heater core from the evaporator case. The temperature blend door can now be visually checked for incorrect welding.
3. The door frame may be held away from a firm seat on the evaporator case by two or three of the plastic weld stakes (along the side closest to the evaporator core). If not secured, it will be loose at the corner closest to the heater core cover.
4. Remove the weld stakes so that the door frame fits flush with the evaporator case. This can be done using a utility knife or a saw blade.
NOTE:
BE SURE TO REMOVE ALL DEBRIS FROM THE CASE, AFTER THIS PROCESS, TO PREVENT VIBRATION NOISES FROM OCCURRING DURING SYSTEM OPERATION.
5. Hold the blend door frame firmly down against the evaporator case and drill two 5/32" (4 mm) holes as shown in Figure 1. Holding the door frame firmly in position, install a 5/32" X 3/8" (4 mm X 9.5 mm) pop rivet in each hole.
CAUTION:
DO NOT USE SCREWS. THE SHARP POINT TENDS TO CATCH ON THE DOOR. BE SURE TO USE 5/32", X 3/8" (4 mm X 9.5 mm) RIVETS. IF A LONGER RIVET IS USED, IT MAY INTERFERE WITH THE BLEND DOOR TRAVEL AND CAUSE FURTHER PROBLEMS.
6. Run a bead of caulking cord along the underside of the door frame on the side nearest the evaporator core, from one corner to the other.
a. Be sure to fill the corners.
b. Use calking cord, Part No. (D6AZ-19560-A), (ESB-M4G32-A) or equivalent.
NOTE:
IT IS VERY IMPORTANT TO GET A GOOD SEAL BETWEEN THE DOOR FRAME AND THE EVAPORATOR CASE, TO PREVENT AIR LEAKAGE THROUGH THE HEATER CORE.
NOTE:
DO NOT USE SILICONE OR OTHER TYPES OF SEALANT THAT HAVE STRONG ODORS. THESE ODORS MAY ENTER THE PASSENGER COMPARTMENT DURING SYSTEM OPERATION.
PART NUMBER PART NAME CLASS
D6AZ-19560-A Rope Caulk (Pk./8) AG
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS:
Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage For 1992/93 Model Vehicles, Basic Warranty Coverage For All Other Model Vehicles
OPERATION DESCRIPTION TIME
940209A Repair Blend Door Seal - 4.1 Hrs.
ATC
940209B Repair Blend Door Seal - 4.2 Hrs.
Manual
DEALER CODING
BASIC PART NO. CONDITION CODE
19D842 61
OASIS CODES: 208000, 208200