ACtion Magazine - September/October 2011 - (Page 36)

Reduced or stopped cooling during a long drive in humid temperatures 2006-2009 Mazda5 and Mazda3 vehicles (including Mazdaspeed3) Some customers with these vehicles may report that the vents start to blow warm air during an extended drive in humid weather. This could be the result of the evaporator freezing and is most likely to occur while driving for an extended time at steady highway speeds with the A/C on MAX in high humidity conditions. During freeze-up, the low pressure pipe will be covered in frost, giving the appearance that it is frozen. Allowing the evaporator to unfreeze will temporarily address the problem. However, there are other conditions that can create similar conditions, including A/C cutoff control operation, where the PCM stops energizing the A/C relay when certain conditions are met. This can include the following situations: • During acceleration with the throttle valve opening angle 50% or more. • When engine coolant temperature (ECT) is 235° F (113° C). The system repeatedly turns on and off every 20 seconds until the ECT is less than approximately 230° F (110° C). • When the ECT is 242° F (117° C) or more. The system will remain off until the ECT decreases to less than 237° F (114° C). These conditions indicate that the engine is running hot and could be on the verge of overheating. • Electrical or mechanical concerns that could restrict vent air flow, causing irregular operation of the blower motor and/or engagement of the A/C compressor. The cause of evaporator freeze-up may be variations in the evaporator temperature sensor and uneven airflow across the evaporator. To correct the sensor problem, a short harness with a built-in resistor should be installed in series with the evaporator temperature sensor circuit. The harness will correct the problem by reducing the measured value 1.8° F (1° C). To correct the airflow problem, the upper cabin filter with a built-in diffuser will need to be installed. Here’s the procedure: 1. Record the customer’s radio station presets and disconnect the battery negative cable for at least one minute. 2. Remove the side wall on the passenger side footwell, then remove the Passenger Junction Box and metal mounting bracket using the correct service information. 3. Disconnect the connector from the evaporator temperature sensor and the power MOSFET, if 36 ACTION • September/October 2011 equipped with automatic climate control. 4. Remove the evaporator access cover from the A/C unit and the upper and lower air filters. 5. Install the replacement upper cabin air filter with diffuser plate (P/N BP8P-61-J6X) and existing lower filter, making sure the arrows marked on the filters are facing toward the rear of the vehicle, then replace the access cover. NOTE: Replacing just the upper filter should correct the problem. If the lower filter is in need of replacement, refer to the correct service information for the proper part number. 6. Install a short harness with resistor (P/N BPY1-61-545A) to the connector, then attach to evaporator temperature sensor. 7. Assemble in reverse order, reconnect battery negative cable, verify repair, enter radio presets and set the clock. Replacement upper cabin air filter with diffuser. Make sure arrows face rear of vehicle for replacement cabin air filter with diffuser (1) and existing lower filter (2).

Table of Contents for the Digital Edition of ACtion Magazine - September/October 2011

ACtion Magazine - September/October 2011
Table of Contents
Outlook
Expansion Valve
Techncally RELAY-ted
Under The Southern Cross
Leonard’s Law
News & Updates
Virtual View
Cooling Corner
Performance Always Needs More Cooling
ACDelco’s Guidelines for Replacing Engine Coolant
Worldwide Training
New Member Profile: Alex Original, Ltd
Association News
Obituary
Quick Check
New Products & Services
Last Watch

ACtion Magazine - September/October 2011