REDUCED HEATER PERFORMANCE REPAIR PROCEDURE AND PARTS
Model and Year: 1987-88 CORSICA, BERETTA
Customer comments on reduced heater performance may be addressed by one or more of the following conditions that have been identified as contributing factors.
Some of the early production vehicles with C41 heater only, may have one or two heater module related conditions that would cause a reduced heat condition. Both of these conditions will allow cold inlet air to bypass the heater core causing reduced temperature of heater outlet air.
The first condition is an incorrect assembly of the heater module separator case to heater core case. The following procedure should be used to address this condition.
Procedure:
--------- 1. Remove the blower air inlet assembly from the front of dash. (Engine Side)
2. Determine the existence of a misalignment by viewing the steel temperature valve door tail edge. If the tail edge of valve door is visible, the case joint requires repositioning (See Figure 2 for viewing direction).
3. Remove the right and left under dash hush panels.
4. Loosen the two screws indicated in Figure 1.
5. Reach in the front of dash opening, (as shown in Figure 2) grasping the top area of separator case and pull forward. The separator case should snap into position.
6. Tighten the two loose screws.
7. Reinstall blower inlet air assembly.
8. Do Not install hush panels until the following condition has been addressed.
Labor Operation Number: T1398
Labor Time : .9 Hours
The second condition is improper sealing of the heater core. This condition may be addressed by installing new service part seals around the heater core. This operation may be done before you install the hush panels from the previous procedure.
Part Number Part Name ---------- --------- 3052253 (2 Required) Heater Core Seal
346769 (2 Required) Heater Core Seal
Parts are currently available from GMSPO.
IMPORTANT: NEW SEALS SHOULD BE INSTALLED ANYTIME THE HEATER CORE IS DISTURBED OR REPLACED.
Use applicable labor operation and time.
The assembly plant breakpoints for these two conditions are as follows:
Assembly Plant VIN -------------- --- Linden JE234793 Wilmington JY228885
The next condition that may cause reduced heater performance is the thermostat on the 2.0L engine. If the engine was built, prior to the following breakpoint, it has a 192 degree " F "thermostat. The 192 degree thermostat should be replaced with a 199 degree "F" thermostat service part number 10045126.
Use applicable Labor Operation and Time.
The last condition that may cause reduced heater performance was addressed in Bulletin 88-102-lA dated December, 1987. This bulletin recommended replacing the floor heater outlets for higher heat air distribution and flow.
The breakpoint for vehicles with the last two conditions at both assembly plants is VIN 500,000.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
