SER25-057
11/21/2025
This bulletin supersedes SER25-018
SUBJECT: Updated Service Procedures for Elevated Coolant Temperature on X4 and Vector
Under certain conditions X4™ and Vector™ units may experience elevated coolant temperature. The purpose
of this bulletin is to provide updated guidance for identifying units that may exhibit this condition, and the
corrective action required.
Model and Serial Numbers Affected
Model
X4 7700
Vector 8700/8800MT/8811MT
X4 7500
Vector 8500/8600MT/8611MT

Serial Number Range
ALL
After VAX91770446

Corrective Action

Model
X4 7700
Vector 8700/8800MT/8811MT
X4 7500
Vector 8500/8600MT/8611MT

Alarms
A26301 Engine Shutdown Alarm with P0217 (Engine Overheat)
or
A26302 Engine Warning Alarm with P3025 (Overheat Precaution)
A00012 High Coolant Temperature

Table 1. TRU Model and Coolant Temperature Alarms

© Carrier Corporation 2025

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Coolant Temperature Verification

Only perform this procedure on trailers that are not loaded.

1. Open the trailer doors.
2. Turn on the TRU.
3. Adjust the setpoint to -22°F (-30°C) for ambient temperatures above 32°F (0°C) or 90°F setpoint (32°C)
for ambient temperatures below 32°F (0°C).
4. Run the TRU for 30 minutes.
5. Check the coolant and ambient temperature values from the unit data menu.
6. Use the chart in Figure 1 to determine if the coolant flush procedure needs to be performed.
Example 1: The ambient temperature is 86°F (30°C) and the coolant temperature is 185°F (85°C). This
is outside the service soon and service immediately ranges so no further action is required.
Example 2: The ambient temperature is 86°F (30°C) and the coolant temperature is 221°F (105°C).
This is within the service soon range and the unit needs to be scheduled to have the coolant flush
procedure performed.

Figure 1. Engine Coolant and Ambient Temperature

© Carrier Corporation 2025

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Cooling System Inspection and Flush Procedure

1

Verify that non-compatible coolant has not been added to the cooling system. Non-compatible
coolants are any coolant that does not meet the specifications listed in step 9. If non-compatible
coolant has been added, flush the cooling system and refill with the correct coolant. Failures that are
a result of adding non-compatible coolants are not warrantable.

2

Visually inspect the unit checking for external condenser/radiator fouling, loose/worn belts, or
external coolant leaks. Correct any issues if found and recheck for high coolant temperature related
alarms.
Remove the hose (1) from the water pump inlet.
Drain coolant into an appropriate container.

3
1

Do not remove the cap from a hot coolant system; if
the cap must be removed, do so very slowly in order to
release the pressure without spray.

Remove thermostat cover mounting screws and
thermostat cover (1).
Remove thermostat assembly (2).

4

Re-install thermostat cover (1).

Refill the cooling system with water and cooling system
cleaner.
Refer to coolant flush bottle for manufacturer
recommended quantity of flush to add per gallon/liter
of system capacity.

5

Cooling system capacity (engine and radiator)
1.55 US gallons (5.86 liters)
Recommended cooling system cleaner/flush:
•
•
•

© Carrier Corporation 2025

CLR Pro Heavy Duty Radiator Flush & Cleaner
Fleetguard Restore
Bluedevil Radiator Flush

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Run the unit.
While the unit is running, observe the coolant reservoir,
if coolant is flowing through the reservoir, pinch the
small line with hose pliers.
Continue running the unit for a total of 1.5 hours.

6

Drain the cooling system.

Refill with water.
Run the unit for 5 minutes and then drain cooling
system.

7

Repeat this step until the water drained is clear.

Install thermostat assembly (2) and new thermostat
cover gasket.

Make sure that the direction of the jiggle valve is
oriented to the coolant temperature sensor.

8

Install the thermostat cover and thermostat cover
mounting screws (1).

5.8 to 6.8 ft-lb
(7.9 to 9.3 Nm)

© Carrier Corporation 2025

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Refill the cooling system with the appropriate coolant.
It is important that the correct type of coolant is installed
anytime the cooling system is serviced.
Note: The factory fill coolant is Shell Rotella ELC
NF.
Coolant Type

9

Color
Specifications

Organic Acid Technology (OAT)
Nitrite Free (NF)
50/50 Antifreeze Coolant (AFC)/
Distilled Water1
Red
ASTM D3306, ASTM D6210

1. Do not exceed 60/40 AFC/Water
Measure 1.3 oz/40ml of (46-00074-00) additive using
a graduated cylinder or syringe.
Add to the cooling system.

10
The required quantity of additive has changed to
1.3 oz/40ml. Do not add the full contents of the bottle to
the cooling system.

Run the unit and verify that the unit is no longer in the service engine coolant system soon or service
immediately zone (Figure 1).

11

If the unit is still in the service engine coolant system soon or service immediately zone, replace the
radiator. Refer to (62-12251 or 62-12259).
If engine damage is suspected, submit an engine authorization request case. Refer to SER22-015
and SER24-021.

Claim information
For coolant temperature verification claims where the coolant temperature was found not to be in the service
engine coolant system soon or service immediately zone, use SER25-057 as the causal part number. Use
labor code S61-H (0.3).
For claims where flushing the cooling system resolved the high coolant temperature condition, use the additive
part number (46-00074-00) as the causal part number. Use labor codes W10-A (2.0) and W2-A (1.0).
For claims where flushing the cooling system did not resolve the high coolant temperature condition and the
radiator was replaced, use radiator part number (08-01083-00) as the causal part number. Use labor codes
W10-A (2.0), W2-A (1.0), and W11-A (4.0).
Coolant flush may be claimed as a non-OEM part with an allowance of $15.00 per claim.
Coolant temperature verification and/or flushing may be claimed once every 12 months or until the unit has
5000 engine hours. Refer to WebClaim 2.0 to verify claim history.

© Carrier Corporation 2025

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