Low Freon level can cause this. Do not try to refill yourself with a can. You will do more damage to it, because you have not evacuated used Freon and keep topping off externally will overload the system and spring a leak or burn the compressor out. Take it to a Shop where they will Evacuate, create Vaccum, inject Compressor oil and Dye and recharge to the require level with Freon. This way if Freon leaks you can see where the dye is coming out and fix the leak.
SOURCE: 1999 1500 silverado heater
Sounds like the blend door in the ducting has failed, this door is what controls the temp of the outlet air by blending heat and outside air or AC cooled air.
SOURCE: 2004 chevy silverado 1500 a/c heater
when my truck is at an idle, it won't put out any heat in the cab, same thing in the summer with the A/C, what's the fix for it ?
SOURCE: 1989 chevy silverado heater blowes cold air. both
Feel the hoses going into the heater on the firewall. If one is hot and the other is cool, then the heater control valve is not working for whatever reason. Check the flow valve.
SOURCE: heater blows cold on 02 chevy silverado 1500 4.3 V6
i had the same problem with my 2000 chevy truck!! i took both hoses off engine and flushed the heater core with water and air frome air compresser,added new coolent and it works perfect!!!! so try flushing your system............
SOURCE: 1999 1500 Chevy Silverado - microchip for anti-theft?
Document ID# 803013
1999 Chevrolet Chevy K Silverado - 4WD
Security Lamp Illuminated on the IP, Engine Stalls, No Start, DTC B2960
(Security System Sensor Data Incorrect but Valid) Set (Inspect and
Repair Cause of DTC B2960)
1999-2001 Chevrolet and GMC C/K Pickup and Utility Models (Silverado,
Sierra, Tahoe, Suburban, Yukon, Yukon XL)
This bulletin is being revised to add information on inspecting for
electrical intermittent conditions and important connector C201
tightening steps. Please discard Corporate Bulletin Number 01-08-56-002
(Section 08 -- Body and Accessories).
Condition
Some customers may comment on the following conditions. These symptoms
may be intermittent.
• Security lamp illuminates while driving. The Security lamp may be
On or Off when the customer brings the vehicle to the service facility.
• The engine cranks but will not start and the Security lamp is
flashing.
• The engine starts then stalls and the Security lamp is flashing.
Cause
Condition(s) may be due to an incorrect Passlock™ sensor voltage
received by the body control module (BCM) from the Passlock™ sensor due
to the following conditions. Most intermittent conditions are caused by
faulty electrical connections or wiring.
• A 7 ohm variation in the sensor ground circuit wiring, circuit
1057
• A 100 ohm variation in the Passlock™ sensor signal wiring circuit,
circuit 1836
Inspect for the following items:
• Broken wiring inside the insulation.
• A poor connection between the male and female terminal at the
connector. Refer to Testing for Proper Terminal Contact under Testing
for Intermittent and Poor Connections in Wiring Systems for the specific
procedure.
• A poor terminal to wire connection. Some conditions that fall
under this description include poor crimps, poor solder joints, crimping
over the wire insulation instead of the wire itself, and corrosion in
the wire to terminal contact area.
• Wire insulation that is rubbed through. This causes an
intermittent short as the bare area touches other wiring or parts of the
vehicle.
• A poor connection between the male and female terminal at a
connector. This poor connection may be the result of contamination or
deformation.
- Contamination may be caused by the connector halves being
improperly connected. A missing or damaged connector seal, damage to the
connector itself, or exposing the terminals to moisture and dirt can
also cause contamination. Contamination, usually in the underhood or
underbody connectors, leads to terminal corrosion, causing an open
circuit or intermittently open circuit.
• Separate the connector halves.
• Visually inspect the connector halves for contamination.
Contamination may result in a white or green build-up within the
connector body or between terminals. This causes high terminal
resistance, intermittent contact, or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced
in its entirety including the terminals, the seals, and the connector
body.
- Deformation is caused by probing the mating side of a connector
terminal without the proper adapter, improperly joining the connector
halves, or repeatedly separating and joining the connector halves.
Deformation, usually to the female terminal connector tang, can result
in poor terminal contact causing an open or intermittently open circuit.
Using an equivalent male terminal from the J 38125-B, test that the
retention force is significantly different between an good terminal and a
suspect terminal. Replace the female terminal in question.
Correction
Have any of the following components had service recently?
• The BCM
• The ignition lock cylinder case assembly
• The PCM/VCM
If any of the above components have been replaced, the Programming Theft
Deterrent System Components procedure must be performed before any
diagnostic procedures are performed.
To assist in diagnosis, the following steps are provided.
Does the engine start? If not, use the Engine Cranks but Does Not Run
diagnostic information in the Engine Controls sub-section of the
applicable Service Manual.
Important:
• The Security telltale on the message center is controlled by the
vehicle theft deterrent (VTD) system and the content theft deterrent
(CTD) system. The Security telltale is controlled by the BCM through the
Class 2 data line.
• The VTD system portion of the BCM controls the Security telltale
when the ignition switch is in the On position. The VTD system uses the
Security telltale as a malfunction indicator.
• The CTD system portion of the BCM controls the Security telltale
when the ignition switch is in the Off position. The CTD system uses the
Security telltale to identify system status.
Observe the Security indicator lamp in the instrument panel.
Remove the key from the lock cylinder.
- Security indicator should be Flashing when the door is open.
- Security indicator should be Off when all the doors are closed.
- If the Security indicator does not come On or go Off correctly,
refer to the Content Theft Deterrent System diagnostic and repair
information in the applicable Service Manual.
With the Doors closed, place the key in the lock cylinder and turn to
the Run position. Observe the Security indicator lamp.
- Lamp is On and does not go Off however, the engine starts. This
indicates that the VTD system detected a fault when the engine was
running.
- Lamp flashes On and Off. This indicates a problem has been
detected by the VTD (Passlock™) system and the engine may not start this
key cycle, a current condition.
Important: You must diagnose the diagnostic trouble codes (DTCs) in the
order specified in the DTC table shown below. Failure to do so may
result in one or more of the following conditions:
• Extended diagnostic time
• Incorrect diagnosis
• Incorrect parts replacement
DTC
Diagnostic Procedure
Module
Important: Before you use this table, diagnose P0601, P0602, P0604, and
P0606. Refer to Diagnostic System Check - Theft Deterrent.
PXXXX Other PCM DTCs
Refer to the following procedures:
• Diagnostic System Check - Engine Controls in Engine Controls -
4.3L
• Diagnostic System Check - Engine Controls in Engine Controls -
4.8L, 5.3L, 6.0
• DTC P0192 in Engine Controls - 6.6L
• Diagnostic System Check - Engine Controls in Engine Controls -
8.1L
If none of the above items are true, proceed with the following steps:
Install seat covers.
Connect the scan tool to the diagnostic link connector (DLC).
Enter scan tool diagnostics.
Select the model year of the vehicle.
Select light truck.
Select F1, (Body).
Select "C" or "K" for Series.
Select F0, Body Control Module.
Select F0, (Diagnostic Trouble Codes (DTC)).
Select F0, (DTC information).
Select F0, (Current DTC).
Record on the repair order any current DTCs displayed. If none, skip the
next step.
Is a current B2960 DTC displayed? If no, the condition is not present
with this key cycle. Continue to the next step.
Select Exit.
Select F1, (History DTC).
Are any history DTCs other than B2960 present? If so, diagnose those
DTCs first using the appropriate service information, otherwise
continue.
Select Exit.
Select Exit.
Select F1, Data Display.
Select F6, Security.
Cycle the key to the OFF position and wait 20 seconds.
Slowly turn the key to the RUN position. Be careful not to turn the key
into the START position.
Observe the following values:
- Passlock™ Data Voltage should be 5.0 volts.
- Passlock™ State should be Normal.
- Passlock™ Code should be Open.
Rotate the key to the START position, and observe the following again:
- Passlock™ Data Voltage should be less than 5.0 volts. Passlock™
Data Voltage should remain steady and not fluctuate. The test vehicle
used for this diagnostic procedure had a voltage value of 2.49 volts.
The vehicle being worked on may be either higher or lower than this
value. The key is that it has to be less than 5.0 volts.
- Passlock™ State should be "Monitor Passlock™".
- Passlock™ Code should be Valid Code.
If no trouble is found and the customer has experienced one of the
symptoms or the code is a history DTC, the most likely cause is the VTD
(Passlock™) wiring, specifically the wires from the VTD (Passlock™)
sensor to the BCM.
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