Mechanics

MY PASSANGER TEMP CONTROL IS STUCK ON HEAT .HOW DO I GET IT TO BLOW COLD AIR?

1999 Chrysler Town and Country • 103,323 miles

I MOVE IT TO COOL AND NOTHING.I HAVE DISCONNECTED THE BATTERY NOTHING. AND I CANT FIND A VACUME LEAK.
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ALLAN
December 28, 2011.



HVAC SYSTEMS - AUTOMATIC- TROUBLE SHOOTING -1999 Chrysler Town & C.
Page 1 of 5
ARTICLE BEGINNING

A/C SYSTEM DIAGNOSIS

RAPID COMPRESSOR CLUTCH CYCLING

Some possible causes of rapid compressor clutch cycling, clutch cycles 10 or more times per minute, include: ? Low refrigerant system charge.
? Faulty low pressure cycling clutch switch. ? Faulty PCM.
COMPRESSOR WILL NOT ENGAGE

Some possible causes of compressor not engaging with high and low side system pressures equal include: ? No refrigerant in system. ? Faulty fuse.
? Faulty compressor clutch coil.
? Faulty compressor clutch relay.
? Faulty electronic cycling clutch switch.
? Improperly installed or faulty low pressure cycling clutch switch. ? Faulty low pressure cut-off switch.
? Faulty high pressure cut-off switch. ? Faulty PCM.
? Faulty A/C-heater control panel.
TEMPERATURE IS TOO HIGH WITH A/C ON

Some possible causes of high temperature output at center panel when A/C system pressure is normal include: ? Excessive oil charge in refrigerant.
? Temperature control cable improperly installed or faulty.
? Blend-air door inoperative, obstructed or sealing improperly. ? Blend door actuator not calibrated.
LOW SIDE PRESSURE IS LOW-TO-NORMAL & HIGH SIDE PRESSURE IS LOW

Some possible causes of low side system pressure being lower-to-normal and high side system

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HVAC SYSTEMS - AUTOMATIC- TROUBLE SHOOTING -1999 Chrysler Town & C.
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pressure being too low include: ? Low refrigerant system charge.
? Refrigerant flow through accumulator is restricted. ? Refrigerant flow through evaporator is restricted.
? Faulty compressor.
LOW SIDE PRESSURE IS HIGH-TO-NORMAL & HIGH SIDE PRESSURE IS HIGH

Some possible causes of low side system pressure being high-to-normal and high side system pressure being too high include: ? Condenser air flow restricted. ? Inoperative cooling fan.
? Faulty expansion valve.
? Refrigerant system overcharged. ? Air in refrigerant system.
? Engine overheating.
LOW SIDE PRESSURE IS HIGH & HIGH SIDE PRESSURE IS LOW

Some possible causes of low side system pressure being too high and high side system pressure being too low include: ? Compressor belt is slipping.
? Fixed orifice tube not installed. ? Faulty compressor.
LOW SIDE PRESSURE IS LOW & HIGH SIDE PRESSURE IS HIGH

Some possible causes of low side system pressure being too low and high side system pressure being too high include: ? Restricted refrigerant flow through refrigerant lines. ? Restricted refrigerant flow through expansion valve.
? Restricted refrigerant flow through fixed orifice tube. ? Restricted refrigerant flow through receiver-drier.
? Restricted refrigerant flow through condenser.
BLOWER MOTOR DIAGNOSIS

BLOWER MOTOR INOPERATIVE

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HVAC SYSTEMS - AUTOMATIC- TROUBLE SHOOTING -1999 Chrysler Town & C.
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Some possible causes of an inoperative blower motor include: ? Faulty fuse.
? Faulty blower motor feed circuit wire harness or connectors.
? Faulty blower motor ground circuit wire harness or connector. ? Faulty blower motor resistor.
? Faulty blower motor relay.
? Faulty blower motor switch.
? Faulty A/C-heater mode control switch. ? Faulty blower motor.
BLOWER NOT OPERATING IN ALL SPEEDS

Possible causes of the blower not operating in all speeds include: ? Faulty fuse.
? Faulty blower motor feed circuit wire harness or connectors. ? Faulty blower motor relay.
? Faulty blower motor resistor. ? Faulty blower motor switch.
BLOWER MOTOR VIBRATION

Possible causes of blower motor vibration include: ? Improper blower motor mounting.
? Improper blower wheel or fan mounting. ? Blower wheel or fan out of balance.
? Blower motor faulty.
BLOWER MOTOR NOISE

Possible causes of blower motor noise include: ? Foreign material in blower motor housing. ? Foreign material in A/C-heater housing.
? Improper blower motor mounting.
? Improper blower wheel or fan mounting. ? Blower motor faulty.
VACUUM CONTROL SYSTEM DIAGNOSIS

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HVAC SYSTEMS - AUTOMATIC- TROUBLE SHOOTING -1999 Chrysler Town & C.
Page 4 of 5
VACUUM CONTROL ONE-WAY CHECK VALVE

NOTE: Some models use brake booster check valve for vacuum source.
These models do not use another in-line vacuum check valve.
1.
In engine compartment, locate Black vacuum hose that runs from brake booster check valve or intake manifold, through firewall near heater hoses or expansion valve. This supply vacuum
hose goes to A/C-heater control panel vacuum switch.
Within Black vacuum hose, disconnect and remove check valve near intake manifold or brake booster. Connect vacuum gauge to an external vacuum pump. Start vacuum pump. Plug end of
hose probe on vacuum gauge. Adjust bleed valve on vacuum gauge to obtain an exact vacuum reading of 8 in. Hg.
Unplug and plug end of hose probe on vacuum gauge several times to ensure exact vacuum reading. Connect vacuum gauge hose probe to control panel side of check valve. Vacuum
gauge reading should be 8 in. Hg. Replace check valve if vacuum leak exists.
Connect vacuum gauge hose probe to engine side of check valve. Vacuum should flow through check valve. Replace check valve if operation is not as described.
2.
3.
4.
VACUUM CONTROLS

1.
This test checks for proper function of control panel vacuum circuits. Perform steps 1) through 4) under VACUUM CONTROL ONE-WAY CHECK VALVE.
Connect vacuum gauge hose probe to Black vacuum hose end that leads to A/C-heater control panel switch. Position vacuum gauge so gauge reading can be observed from inside vehicle.
Operate A/C-heater controls (sliding lever or push buttons) in all mode positions (floor, defrost, panel, etc.). Pause after each selection to allow vacuum actuators or motors to energize
and stabilize. Record vacuum gauge reading at each selection.
After each selection, vacuum reading should be 7.5-8 in. Hg. Maximum vacuum reading drop is.75 in. Hg. If proper vacuum reading cannot be obtained, vacuum leak exists in selected
circuit.
To check for vacuum leak(s), disconnect 7-way A/C-heater control panel vacuum harness connector. See Fig. 1. If necessary, remove control panel from instrument panel to access A/C-
heater control panel vacuum harness connector, or remove lower instrument panel assembly.
Connect vacuum source probe to each port of connector. See Fig. 1
gauge reading. Vacuum reading should be 8 in. Hg at each port.
2.
3.
4.
5.
. Record each vacuum
6.
NOTE: Brown (bi-level) vacuum circuit contains a restriction in line. It
takes longer to obtain correct vacuum reading on this line.
7.
If correct vacuum readings are obtained, replace faulty A/C-heater control panel vacuum switch assembly. If proper vacuum readings are not obtained, check appropriate vacuum
circuit.
Start vacuum check by plugging vacuum hose at vacuum actuator in suspect circuit. Recheck vacuum circuit by connecting vacuum source probe to proper port.
If proper vacuum reading is now obtained, replace vacuum actuator. If proper reading is not obtained, check vacuum hoses and connections for leak. Repair or replace as required.
8.
9.

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HVAC SYSTEMS - AUTOMATIC- TROUBLE SHOOTING -1999 Chrysler Town & C.
Page 5 of 5
Fig. 1: Testing A/C-Heater System Vacuum Control Circuits Courtesy of CHRYSLER CORP.
TROUBLE SHOOTING

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BuddyMac
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Fig. 2: Blower Motor System Diagnosis (Except RWD Van) Courtesy of CHRYSLER CORP.
Fig. 3: Blower Motor & Control System Diagnosis (RWD Van) Courtesy of CHRYSLER CORP.
Fig. 4: Blower Motor Noise & Vibration Diagnosis Courtesy of CHRYSLER CORP.
Fig. 5: A/C Compressor & Compressor Clutch Diagnosis (1 Of 2) Courtesy of CHRYSLER CORP.
Fig. 6: A/C Compressor & Compressor Clutch Diagnosis (2 Of 2) Courtesy of CHRYSLER CORP.
Fig. 7: A/C Diagnosis - Fixed Displacement Compressors Courtesy of CHRYSLER CORP.


Rivermikerat
Dec 28, 2011.