A/C - Reduced Heater Temperature Output At Idle
TSB 09-5-203/23/09
3.5L - REDUCED HEATER DUCT DISCHARGE TEMPERATURE AT IDLE
LINCOLN:
2009 MKZ
ISSUE
Some 2009 Lincoln MKZ vehicles equipped with a 3.5L engine may exhibit a customer concern of reduced heater duct discharge temperature when the vehicle engine speed is brought down to an idle
ACTION
Follow the Service Procedure steps to correct the condition.
SERVICE PROCEDURE
1. Check the sealing surface on the degas bottle filler neck for nicks or cuts. If a defect is observed, pressurize the cooling system to 15 psi (100 kPa).
a. If pressure holds for two minutes proceed to Step 2.
b. If pressure cannot be maintained for two minutes.
(1) Replace the degas bottle. Refer to Workshop Manual (WSM), Section 303-03.
(2) Refill cooling system with 50/50 mix of coolant.
2. Test the cooling system for trapped air using the following procedure.
a. Idle the engine until it is fully warmed up.
b. If cooling fans are running, idle until fans switch off.
c. Turn engine off and wait 1 minute before carefully removing pressure cap.
WARNING
IF AIR IS TRAPPED IN THE ENGINE, COOLANT MAY BE EXPELLED IF THE CAP IS OPENED TOO QUICKLY. WAIT 1 MINUTE BEFORE REMOVING THE CAP.
d. Attach cooling system pressure tester to degas bottle neck. Refer to WSM, Section 303-03.
e. Note level of coolant in bottle.
f. Apply pressure of 15 psi (100 kPa) to the cooling system.
g. If the coolant level drops by more than 9/16" (15 mm), then air is trapped in the cooling system.
h. Remove the pressure tester and top off the cooling system.
i. Install degas bottle cap.
3. If air is present, remove the air from the cooling system using the procedure below.
a. Idle engine until the fan turns on, indicating the thermostat is fully open.
b. Increase engine speed to 2500 RPM for 30 seconds.
c. Idle engine for 2 minutes.
d. Repeat steps (b) and (c) five (5) times.
e. Top-off with 50/50 coolant mix if required.
4. Verify satisfactory heater performance at idle using the Heater Performance Evaluation procedure below.
NOTE
ON COLDER AMBIENT TEMPERATURES THE HEATER PERFORMANCE IS LIMITED OR REDUCED, THIS IS NORMAL HEATER OUTPUT EFFICIENCY IN EXTREME COLD TEMPERATURES.
a. Heater Performance Evaluation
(1) Idle the engine at shop ambient temperature of 60 °F (15 °C) or higher, until the engine is fully warmed up.
(2) Set the control head to 90 °F (32 °C).
(3) Set the mode to panel/vent and ensure A/C is switched-off.
(4) Set the blower to highest speed.
(5) Idle the engine for 5 minutes with the hood down.
(6) The left-center vent discharge air temperature should be a minimum of 150 °F (65 °C).
b. If the required performance is not met then complete Steps 5 through 22.
c. If heater performance is met, return the vehicle to the customer.
5. Drain coolant using WSM, Section 303-03.
6. Remove battery, using WSM, Section 414-01, to gain access to thermostat housing.
7. Back flush heater core through heater return hose with tap water for 2 minutes.
8. Attach a drain hose to heater return port on thermostat housing to prevent coolant from splashing and staining the engine compartment.
9. Flush engine through heater feed port on thermostat housing with tap water for 3 minutes (Radiator drain should still be open and pressure cap installed).
10. Reconnect cooling system hoses and close radiator drain valve.
11. Add one (1) bottle of Motorcraft(R) Premium Cooling System Flush to the degas bottle. (Do not use Motorcraft(R) Cooling System Cleaner F8AZ-19A503-AA or Motorcraft(R) Engine Cooling System Iron Cleaner VC-9, this is for rust removal and will not remove coolant silicate gel residue.)
12. Add tap water to the degas bottle until the water reaches the maximum of the cold fill range.
13. Install the degas bottle pressure cap.
CAUTION
THE FLUSHING SOLUTION CONTAINS NO GLYCOL, THE SYSTEM WILL BOIL BEFORE THE FANS TURN ON IF THE PRESSURE CAP IS NOT FITTED CORRECTLY.
14. Idle the engine for an additional 5 minutes.
15. Run the engine for 10 minutes at 2500 RPM to clean the cooling system.
CAUTION
IF THE ENGINE OVERHEATS OR THE FLUID LEVEL DROPS BELOW THE MINIMUM FILL LINE, SHUT OFF THE ENGINE AND ADD FLUID TO THE DEGAS BOTTLE MAXIMUM FILL LINE ONCE THE ENGINE COOLS. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN DAMAGE TO THE ENGINE.
16. Drain coolant using Workshop Manual (WSM), Section 303-03.
17. Remove battery, using WSM, Section 414-01, to gain access to thermostat housing and remove both of the attached heater hoses.
18. Repeat Steps 7 through 15 to clean the flushing solution out of the cooling system.
19. Refill and add 5.5 quarts (5.2 L) of coolant concentrate, Motorcraft(R) Premium Gold Engine Coolant with Bittering Agent to the cooling system.
20. Measure coolant concentration and adjust to achieve a 50/50 mix. Set the fill level at the maximum of the cold fill range.
21. Install the degas bottle pressure cap.
22. Bleed air from the cooling system using the Removing Air from Cooling System procedure in Step 3 and top-off with 50/50 coolant mix if required.
23. Verify satisfactory heater per[ormance at idle using the Heater Performance Evaluation procedure.
a. If heater performance is met, return the vehicle to the customer and do not continue with this procedure.
b. If heater performance is not satisfactory then proceed to Heater Core Replacement.
Heater Core Replacement
1. Replace the heater core, refer to WSM, Section 412-01.
2. Refill cooling system with 50/50 mix of coolant. Set the fill level at the maximum of the cold fill range.
3. Bleed air from the cooling system, following Step 22, under Cooling System Flush and top-off with 50/50 mix of coolant.
4. Run the vehicle for 10 minutes at 2500 RPM (to stabilize the coolant silicate concentration in the cooling system) before returning vehicle to the customer.
WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.
Parts Block
OPERATION DESCRIPTION TIME
090502A 2009 MKZ 3.5L Engine: 0.9 Hr.
Inspect Coolant Bottle
Pressure Test System,
Check For Air In System,
Bleed Air From System,
Check Heater Performance
(Do Not Use With 18476A,
7210A, 7326C, 8080A)
090502B 2009 MKZ 3.5L Engine: 1.0 Hr.
Inspect Coolant Bottle,
Pressure Test System,
Replace Coolant Bottle,
Check For Air In System,
Bleed Air From System,
Check Heater Performance
(Do Not Use With 18476A,
7210A, 7326C, 8080A)
090502C 2009 MKZ 3.5L Engine: 2.4 Hrs.
Inspect Coolant Bottle,
Pressure Test System,
Check For Air In System,
Flush Heater Core, Bleed
Air From System, Check
Heater Per[ormance (Do
Not Use With 18476A,
7210A, 7326C, 8080A)
090502D 2009 MKZ 3.5L Engine: 2.6 Hrs.
Inspect Coolant Bottle,
Pressure Test System,
Replace Coolant Bottle,
Check For Air In System,
Flush Heater Core, Bleed
Air From System, Check
Heater Performance (Do
Not Use With 18476A,
7210A, 7326C, 8080A)
090502E 2009 MKZ 3.5L Engine: 6.7 Hrs.
Inspect Coolant Bottle,
Check For Air In System,
Check Heater
Performance, Flush Heater
Core, Replace Heater
Core, Bleed Air from
System Check Heater
Performance (Do Not Use
With 18476A, 7210A,
7326C, 8080A)
090502F 2009 MKZ 3.5L Engine: 7.3 Hrs.
Inspect Coolant Bottle,
Pressure Test System,
Replace Coolant Bottle,
Check For Air In System,
Bleed Air From System,
Check Heater
Performance, Flush Heater
Core, Replace Heater
Core, Bleed Air from
System Check Heater
Performance (Do Not Use
With 18476A, 7210A,
7326C, 8080A)
DEALER CODING
CONDITION
BASIC PART NO. CODE
8A080 53
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