Question about 1999 Chevrolet Silverado 1500

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No upper air

No heat or coolimg from upper ducts

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Need to take the cover off the bottom of heater control box and see if that door is shutting

Posted on Oct 01, 2009


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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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2006 Silverado, with a/c running and cold on both sides for 2 hours or so then the drivers side gos hot passengers side cold at the same time.

Manual or automatic climate control ?
Have you had the HVAC control panel checked for DTC'S - diagnostic trouble codes ?

Air Temperature Sensors
The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
• Ambient Air Temperature Sensor
• Inside Air Temperature Sensor Assembly
• Upper Left Air Temperature Sensor
• Upper Right Air Temperature Sensor
• Lower Left Air Temperature Sensor
• Lower Right Air Temperature Sensor
A signal and a low-reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40°C (-40°F) to 101°C (215°F). The sensor signal varies between 0-5 volts.
The input of the duct air temperature sensors are different from the ambient and inside sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease.

• DTC B0174 Output Air Temperature Sensor (Upper Left) Circuit Range/Performance
• DTC B0179 Output Air Temperature Sensor 2 (Lower Left) Circuit Range/Performance
• B0414 is for the left air temperature actuator.
B0408 is for the left air temperature actuator.
DTC B0989 Output Air Temperature Lower Sensors Correlation
The HVAC control module monitors the upper left and upper right duct temperature sensors when the mode switch is in the VENT or BI-LEVEL positions. The HVAC control module monitors the lower left and lower right duct temperature sensors when the mode switch is in the DEFOG, FLOOR or FRONT DEFROST positions. The duct sensors are used to measure the temperature of the air exiting the ducts to help maintain a consistent cabin air temperature. These duct sensor inputs provide the HVAC control module a way to determine if the engine needs to be started to maintain a specific air temperature. If an upper duct sensor circuit failure is detected the HVAC module will not request an engine start to help cool the cabin. A lower duct sensor circuit failure will not prevent the engine from starting.
DTC B0990 Output Air Temperature Upper Sensors Correlation
Your best bet , take it to a qualified repair shop .

May 27, 2017 | Cars & Trucks

1 Answer

After a front end collision the lights in my consel as well as my dome light and my floor heat no longer work

Lighting may be as simple as a fuse, or may even have the switch in the off position. As far as floor heat, is heat coming out of the upper ducts? If not, the shop may not have properly filled your cooling system since your heater works by using the heated coolant. Your cooling system requires purging of captured air within the system whenever the system is drained. If you have heat from upper ducts and not the lowers, the doors built into the heating/cooling system are not working properly. A severe collision may have broken some of the plastic casing of the system causing a mechanical interference of moving parts, or knocked a wire connection loose that controls the doors. Those are the items to visually check. Otherwise it's a process of elimination via testing of the electronics.

Jan 11, 2014 | 2003 Chevrolet Cavalier

1 Answer

Why does air keep getting into my cooling system

are you bleading thr coolimg system before starting to drive the vechicle

Dec 26, 2011 | 1996 Ford Explorer

1 Answer

Where is the air conditioning sensor. We were told it is under the dash and the whole dash has to be dismantled. We were also told there is more than one air conditioning sensor.This is big bucks and not...

The upper and lower duct sensors are divided into left and right zone operation. The left side upper and lower duct sensors will only effect the operation of the left air temperature actuator and the right side upper and lower duct sensors will only effect the operation of the right air temperature actuator. The duct sensors are used to measure the temperature of the air exiting the ducts.

The inside temperature sensor operates within a temperature range between -6.5°C (20.3°F) to 57.5°C (135.5°F) . If the sensor is shorted to ground, the system will operate in the maximum cooling mode. If the sensor is shorted to voltage or open, the system will operate in the maximum heating mode. The ambient sensor operates within a temperature range between-30°C(-22°F) to 51°C (123.8°F) . If the HVAC control module (IPM) has determined that the ambient air temperature sensor has failed, the IPM shall display "- -" in place of the ambient air temperature. If the sensor is shorted to ground, the system will operate in the maximum cooling mode. If the sensor is shorted to voltage or open, the system will operate in the maximum heating mode.

You are not makining sense when you replaced a P/S belt and A/C is now non op You need to know what the pressure is Leave the sensor alone the problem reside in the engine compartment

Jul 11, 2011 | Cadillac SRX Cars & Trucks

1 Answer

Where is the heater core located

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1 Clip
2 Dust and Pollen Filter
3 Air intake housing
4 Defroster air outlet
5 Side window air outlet
6 Heating and A/C controls
7 Air outlets
8 Instrument panel cross member
9 Defroster duct
10 Servo motor for fresh/recirculating air door -V154-
11 Ambient temperature switch -F38-
12 Gasket
13 Evaporator water drain guide
14 Heating and A/C unit
- Heater core
- Evaporator
15 Fresh air blower -V2-
16 Fresh air blower series resistance with fuse -N24-
17 Center air outlet
18 Control panel trim
19 Center trim
20 Heating and A/C cables
21 Heater core
22 Left rear duct
23 Lower duct
24 Upper duct
25 Footwell air outlet
26 Instrument panel cross member, left side member securing bolt
27 Relay
28 A/C cut-off control module -J314-
29 Instrument panel
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Jun 03, 2011 | 2000 Volkswagen Passat 4Motion

1 Answer

Heating system do not work. It started a couple of weeks ago. When set at 70, it produced no warm air. cold air would come from the vent/duct. when increasted to about 76, it would produce heat. Now it do...

I have the exact same problem. Started occasionally blowing cold air. Now I can't get the hot air to come through. Could it be a flapper door that open and closes depending on the tempurature setting?

Jan 04, 2011 | 2006 Lincoln Mark LT

1 Answer

How to replace heate core 1988 buick reagal

  1. Negative battery cable.
  2. Drain cooling system.
  3. Upper firewall weatherstrip.
  4. Upper secondary cowl.
  5. Heater hoses from core.
NOTE Blowing out residual coolant from inside the heater core will prevent coolant leakage into the passenger compartment when the heater core is removed.

  1. Sound insulator.
  2. Rear seat duct adapter.
  3. Heater duct.
  4. Heater core cover.
  5. Heater core.

  1. Heater core.
  2. Heater core cover.
  3. Heater duct.
  4. Rear seat duct adapter.
  5. Sound Insulator.
  6. Heater hoses to core.
  7. Upper secondary cowl.
  8. Upper firewall weatherstrip.
  9. Fill cooling system and check for leaks.
  10. Negative battery cable.



Oct 21, 2010 | 1988 Buick Regal

1 Answer

My rear heating fan cannot supply hot air through roof duct but AC works

Heat is only supplied through floor ducts, as hot air tends to rise up to ceiling to create circulation of hot air inside the car, same way cold air (AC) is only supplied through roof ducts as cold air tends to settle down.

Feb 09, 2010 | 2003 Toyota Sienna

1 Answer

My 1999 s10 has no floor heat

sounds like your switch or your flap inside the duct is not working properly

Jan 02, 2010 | 1999 Chevrolet S-10 Pickup

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