A/C guru's wanted!

topo4u2 · April 29, 2003

Hi all, this is going back to a previous post but here goes:

I had my A/C inspected today for a reasonable fee of 60bucks. ok, turns out that all the pressures are fine. I have an electrical problem. Apparently there is no power coming from the light green wire from the ac control module to the ac relay.

Anyone know where this module is located? and how hard to get at???? When i push the button in on dash the little light does not come on. Hope this is all it is....may help someone else with the same problem.

topo4u2 · April 29, 2003

I put a pic of this circuit at www.picturetrail.com/topo4u2 if you can make it out.

Any help would be appreciated.

asepgrad98 · April 29, 2003

this is for a 98 , i caint get 95..

Document ID# 456487

1998 GMC Truck GMC K Pickup - 4WD

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Heater Blower Controls Components

Name

Location

Locator View

Connector End View

Auxiliary Blower Motor

Behind the right rear wheelhousing

HVAC Component Views

HVAC Connector End Views

Auxiliary Blower Motor Relay, High

On the top of the auxiliary HVAC plenum, near the right rear wheelhousing

HVAC Component Views

HVAC Connector End Views

Auxiliary Blower Motor Relay, Low

On the top of the auxiliary HVAC plenum, near the right rear wheelhousing

HVAC Component Views

HVAC Connector End Views

Auxiliary Blower Motor Relay, Medium

On the top of the auxiliary HVAC plenum, near the right rear wheelhousing

HVAC Component Views

HVAC Connector End Views

Auxiliary Blower Resistor

On the top of the auxiliary HVAC plenum, near the right rear wheelhousing

HVAC Component Views

HVAC Connector End Views

Auxiliary HVAC Control Module

On the front of the overhead console, near the windshield

HVAC Component Views

HVAC Connector End Views

Blower Motor, Front

To the right of the IP, behind the IP compartment box

HVAC Component Views

HVAC Connector End Views

Blower Motor Relay, High

Behind the IP compartment box, on the HVAC plenum

HVAC Component Views

HVAC Connector End Views

Blower Resistor

On top of the HVAC plenum

HVAC Component Views

HVAC Connector End Views

HVAC Control Module

Part of the heater controls, in the center of the IP, under the radio

HVAC Component Views

HVAC Connector End Views

IP Fuse Block

To the left of the IP, near the left front door jamb switch

Power and Grounding Component Views in Wiring Systems

Power and Grounding Connector End Views in Wiring Systems

Recirculation Door Motor

Under the IP, on the HVAC plenum

HVAC Component Views

HVAC Connector End Views

Temperature Door Motor

Under the IP, on the center of the HVAC plenum

HVAC Component Views

HVAC Connector End Views

Underhood Fuse Block

In the left rear side of the engine compartment, on the fender

Power and Grounding Component Views in Wiring Systems

Power and Grounding Connector End Views in Wiring Systems

C100

Part of the engine harness to IP harness, in the left rear side of the engine compartment, at the bulkhead

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C203

Behind the right side of the IP, near the heater motor, in foam wrap

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C205

At the convenience center

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C221

At the convenience center

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C230

Behind the right side of the IP, above the HVAC evaporator housing

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C300

In the overhead console

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C400

At the right rear of the vehicle, above the auxiliary blower motor

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

C401

At the right rear of the vehicle, above the auxiliary blower motor

Harness Routing Views in Wiring Systems

Inline Harness Connector End Views in Wiring Systems

D104 (4.3L, 5.0L, 5.7L)

Part of the engine harness, approximately 20 cm (8 in) from the A/C compressor clutch connector

--

D104 (6.5L)

Part of the engine harness, approximately 28 cm (11 in) from the A/C compressor clutch connector

--

D104 (7.4L)

Part of the engine harness, approximately 17 cm (6.5 in) from the A/C compressor clutch connector

--

G200

Behind the left side of the IP, below the fuse block, on the tie bar

Power and Grounding Component Views in Wiring Systems

--

G202

On the right side of the instrument panel, mounted to the HVAC plenum bracket

Power and Grounding Component Views in Wiring Systems

--

G400 (Utility/Suburban)

On the right side B pillar, near the door striker

Power and Grounding Component Views in Wiring Systems

--

P101

In the right rear side of the engine compartment, at the bulkhead

Harness Routing Views in Wiring Systems

--

S102 (6.5L)

Engine harness approx. 6.5 cm (2.5 in) from the trans connector breakout, towards the starter solenoid harness breakout

--

S103 (4.3L, 5.0L, 5.7L)

Engine harness, approx. 8 cm (3 in) from the EGR valve breakout, toward the taillamp harness breakout

--

S103 (6.5L)

Engine harness, approx. 12 cm (4.7 in) from the starter solenoid breakout, towards the underhood lamp harness breakout

--

S103 (7.4L - A/T)

Engine harness, approx. 8 cm (3 in) from the EGR valve harness breakout, towards the ignition coil harness breakout

--

S103 (7.4L - M/T)

Engine harness, approx. 4 cm (1.5 in) from the fuel injector harness breakout, towards the taillamp harness breakout

--

S107 (4.3L, 5.0L, 5.7L)

Engine harness, approx. 20 cm (8 in) from the EGR valve breakout, toward the taillamp harness breakout

--

S107 (6.5L, HD

Engine harness, approx. 40 cm (15 in) from the EBCM breakout, toward the transmission harness breakout

--

S107 (7.4L)

Engine harness, approx. 18 cm (7 in) from the EBCM breakout, toward the EGR harness breakout

--

S110 (4.3L, 5.0L, 5.7L)

Engine harness, approx. 23 cm (9 in) from the EBCM breakout, toward the taillamp harness

--

S110 (6.5L)

Engine harness, approx. 4 cm (1.5 in) from the EBCM breakout, toward the taillamp harness breakout

--

S110 (7.4L-A/T)

Engine harness, approx. 26 cm (10 in) from the EBCM breakout, near the taillamp harness breakout

--

S145 (7.4L)

Engine harness, approx. 11 cm (4 in) into the EGR valve breakout

--

S147 (Gas)

Engine harness, approx. 5 cm (2 in) from the EGR valve breakout, toward the taillamp harness breakout

--

S147 (Diesel)

Engine harness, approx. 4 cm (1.5 in) from the starter motor solenoid breakout

--

S185

At Diode D104

--

S186

At Diode D104

--

S204

IP harness, approx. 10 cm (4 in) from C100, towards data link connector (DLC)

--

S212

IP harness, approx. 8 cm (3 in) from the inflatable restraint switch breakout

--

S217

IP harness, approx. 16 cm (6 in) from the instrument cluster harness breakout, toward the radio connectors breakout

--

S218

IP harness, approx. 16 cm (6 in) from the inflatable restraint switch breakout

--

S244

HVAC harness, approx. 8 cm (3 in) from the recirculation door breakout, toward the high blower motor relay

--

S268

IP harness, approx. 7 cm (2.5 in) into the HVAC control switch harness breakout

--

S298

IP harness, approx. 24 cm (9.5 in) from the instrument cluster breakout, toward the radio breakout

--

S307 (4-Door Utility/Suburban)

Rear HVAC control harness, approx. 10 cm (4 in) from the auxiliary HVAC control logic module breakout, toward the front auxiliary HVAC control module

--

S308 (4-Door Utility/Suburban)

Rear HVAC control harness, approx. 5 cm (2 in) from the auxiliary HVAC control logic module breakout, toward the rear auxiliary HVAC control module

--

----

S400 (w/Auxiliary A/C)

Auxiliary A/C harness, approx. 17 cm (6.5 in) from the blower motor relays, toward the blower motor

--

S410 (2-door Utility)

Front-to-rear body harness, approx. 37 cm (14.5 in) from the right rear door jamb switch breakout, toward the right rear door speaker breakout

--

S410 (4-Door Utility/Suburban)

Front-to-rear body harness, approx. 12 cm (4.5 in) from the right rear door speaker breakout, toward the right rear door jamb breakout

--

S440 (4-door Utility/Suburban)

Front-to-rear body harness, approx. 6 cm (2.5 in) from the convenience center harness breakout

--

S440 (4-Door Utility/Suburban w/o C69

Front-to-rear body harness, approx. 7 cm (2.5 in) from the crossbody harness breakout, toward the front dome lamp breakout

--

S441 (4-Door Utility/Suburban)

Front-to-rear body harness, approx. 5 cm (2 in) from the convenience center harness breakout

--

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Document ID# 456487

1998 GMC Truck GMC K Pickup - 4WD

topo4u2 · April 29, 2003

Thanks for the info asegrad 98,

Im not sure how close the 98 and 95 are but it looks like that module is incoperated with the controls.

I will check it out this week.thanks.

topo4u2 · April 30, 2003

I have been searching throught this problem but I have 2 confliciting diagrams......anyone have a wiring diagram for the A/C relay??? Need to find where the four wires go??? and colors please.

topo4u2 · May 2, 2003

I was able to get a hold of a decent wiring diagram. It turns out that the light green wire is giving me all the greif. I pulled out the switch assembly in dash tonight. Bypassed the green wire and presto the clutch engages. Well, the fun, there is a small circuit board involved in the switch assembly, my guess is its the culprit. I will contact GM in the am and ask if it can be purchased separately? It would be easy to change, and hopefully not too pricey?

Any one come across this or have any ideas to share please do.