1999 DODGE RAM heater

Fig. 13: Manual A/C-Heater System Wiring Diagram (Dakota - 2.5L)

Fig. 14: Manual A/C-Heater System Wiring Diagram (Dakota - 3.9L, 5.2L
& 5.9L)

Fig. 15: Manual A/C-Heater System Wiring Diagram (Ram Pickup)


A/C -H EA TE R S YSTE M T R O UBLE S H O OTIN G

1999 D odge P ic ku p R 1500
1999 MANUAL A/C-HEATER SYSTEMS
Trouble Shooting - Cars & Trucks
CHRYSLER
Avenger, Breeze, Caravan, Cirrus, Concorde, Dakota, Durango,
Intrepid, LHS, Neon, Ram Pickup, Ram Van/Wagon, Sebring Convertible,
Sebring Coupe, Stratus, Town & Country, Voyager, 300M
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 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
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
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.
2) 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.
3) 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.
4) 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.
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.
2) 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.
3) 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.
4) 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.
5) 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.
6) Connect vacuum source probe to each port of connector. See
Fig. 1. Record each vacuum gauge reading. Vacuum reading should be 8
in. Hg at each port.
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.
8) Start vacuum check by plugging vacuum hose at vacuum
actuator in suspect circuit. Recheck vacuum circuit by connecting
vacuum source probe to proper port.
9) 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.
Fig. 1: Testing A/C-Heater System Vacuum Control Circuits
Courtesy of Chrysler Corp.
TROUBLE SHOOTING

be detected if leak testing is performed too quickly.
BUBBLE DETECTOR LEAK TESTING PROCEDURE
This leak detection method is recommended when it is
impossible or difficult to determine the exact location of the leak
using other methods. Although commercial bubble detectors are more
effective, household soap solutions may be used.
Using the dauber that comes with the commercial soap
solution, apply the solution to all joints, connections, fittings or
controls where a leak might be suspected. If high-suds household
solutions are used, apply them with a small brush. Wherever bubbles
form, leaks are present and must be repaired. check the entire system
as there may be more than one leak.
ELECTRONIC LEAK TESTING PROCEDURE
NOTE: Some electronic leak detectors will function on only R-12
systems or on only R-134a systems, and some will function on
both R-12 and R-134a systems. Familiarize yourself with the
tester being used and know what type of system you are leak
testing.
Electronic leak detectors should be used in well ventilated
areas. Avoid using them around explosive gases. Always follow
manufacturer's instructions for the specific tester being used. If
none are available, proceed as follows:
1) Turn all controls and detector sensitivity knob to OFF
position or zero setting. Connect leak detector to an approved source
of power. Turn switch ON, and allow unit to warm up for approximately
5 minutes.
2) Check operation of tester by positioning probe in a
reference source where refrigerant is known to be present in small
amounts. Adjust controls and sensitivity knob until detector reacts
properly. Move probe away from refrigerant source and the reaction
should stop. If it continues, adjust the sensitivity knob to a lower
setting.
3) When tester reacts properly, leak test air conditioning
system by moving probe UNDER all components, fittings and connections.
Keep the probe moving. To check evaporator insert probe into drain
tube opening or a heater duct. DO NOT allow probe to contact
refrigerant or refrigerant oil. When leaks are found, repair them as
necessary. Keep in mind that there may be more than one leak.
DYE SOLUTION LEAK TESTING PROCEDURES
CAUTION: Dye-charged refrigerant cans are available to be used as
internal leak detectors. The use of this type of solution may
void some manufacturer's warranties. Be sure to check with
the A/C system manufacturer concerning the use of dye-charged
leak detectors. Dyes which work in R-12 systems will not work
in R-134a systems.
The following procedure is for introducing a dye solution,
not dye-charged refrigerant, into A/C system.
1) Connect manifold gauge set to air conditioning system in a
normal manner. Remove center hose from manifold gauge set, and replace
it with a short piece (6" long) of 1/4" tubing using two 1/4" flare
nuts. Connect a container of dye solution to the tubing.
2) Connect one end of gauge set center hose to dye solution
container. Connect a container of refrigerant to the other end of the
hose. Operate engine at idle speed. Set the air conditioning system
for maximum cooling. Slowly open the low-side hand valve to allow the