2005 Silverado fan fuse requirements

[RedHeartbeat]

Anyone running fuses in their 2005 fans? My 30 amp fuses weren't enough. How big of a fuse do we need to run? My A/C don't work without the fans in stop and go traffic. It gets pretty hot running the heater to cool the engine in 105 degree weather too. I'm thinking about going to a thermal breaker so I don't get stranded without electric fans the next time they overheat.

[SCIV]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 18 2006, 04&#58;33 PM) [snapback]58332[/snapback]</div>

Anyone running fuses in their 2005 fans? My 30 amp fuses weren&#39;t enough. How big of a fuse do we need to run? My A/C don&#39;t work without the fans in stop and go traffic. It gets pretty hot running the heater to cool the engine in 105 degree weather too. I&#39;m thinking about going to a thermal breaker so I don&#39;t get stranded without electric fans the next time they overheat.
[/b]

Funny you should post, same problem, but caused more damage. Truck is at the dealership now. Relay was out, no A/C. Head pressure spiked over 450 psi or something, blew the pressure release. Now low on freon and possibly more unknown damage.

Techs won&#39;t warranty because of the &#39;05 fans & relay problem. Looking at &#036;140 bill, plus a voided warranty. Hopefully they at least won&#39;t void the warranty & just let me pay the bill to get it back working.

It was 103* today. This f&#39;in sucks. Allen, I&#39;m coming down there to kick your ass (and you can put my stall in while I&#39;m there&#33

Back on track here, I replaced the relay with a 30/40 amp from O&#39;stupids & is still working for now.

[hummertech]

<div class='quotetop'>QUOTE(SCIV &#064; Jul 18 2006, 04&#58;41 PM) [snapback]58336[/snapback]</div>

Funny you should post, same problem, but caused more damage. Truck is at the dealership now. Relay was out, no A/C. Head pressure spiked over 450 psi or something, blew the pressure release. Now low on freon and possibly more unknown damage.

Techs won&#39;t warranty because of the &#39;05 fans & relay problem. Looking at &#036;140 bill, plus a voided warranty. Hopefully they at least won&#39;t void the warranty & just let me pay the bill to get it back working.

It was 103* today. This f&#39;in sucks. Allen, I&#39;m coming down there to kick your ass (and you can put my stall in while I&#39;m there&#33

Back on track here, I replaced the relay with a 30/40 amp from O&#39;stupids & is still working for now.
[/b]

thets a warranty issue, the clutch should have turned off at 429 psi to prevent a/c system damage. hear is the official description of the a/c operation. if they try to void the warranty than let me know and i can get you a phone number to call to get it handled. the dealership doesnt have to do that. gm a/c systems have to many issues of there own, they brake all the time, this might have happened even with the fans working. there is no way to tell that the fans caused the problem (even though they might have)... anyhow hears some info

A/C Refrigerant Pressure Sensor
The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5 volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts. The PCM converts the voltage signal to a pressure value.

The A/C refrigerant pressure sensor protects the A/C system from operating when an excessively high pressure condition exists. The PCM disables the compressor clutch if the A/C pressure is more than 2957 kPa (429 psi). The clutch will be enabled after the pressure decreases to less than 1578 kPa (229 psi).


A/C Low Pressure Switch
The A/C low pressure switch protects the A/C system from a low pressure condition that could damage the A/C compressor or cause evaporator icing. The HVAC control module applies 5 volts to the A/C low pressure switch signal circuit. The switch will open when the A/C low side pressure reaches 138-172 kPa (20-25 psi). This prevents the A/C compressor from operating. The switch will then close when A/C low pressure side reaches 275-317 kPa (40-46 psi). This enables the A/C compressor to turn back ON.

Heating and A/C Operation
The purpose of the heating and A/C system is to provide heated and cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. The vehicle passenger can offset the passenger temperature as much as 16.7°C (30°F). Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature:

• Recirculation actuator setting

• Difference between inside and desired temperature

• Difference between ambient and desired temperature

• Blower motor speed setting

• Mode setting

The control module makes the following actions when automatic operation is not selected, and an air temperature setting is selected:

• When the air temperature switch is placed in the warmest position, the control module commands the air temperature door to divert maximum air past the heater core.

• When the air temperature switch is placed in the coldest position, the control module commands the air temperature door to direct air to bypass the heater core.

• When the air temperature switch is placed between the warmest and coldest positions, the control module monitors the following sensor inputs to determine the air temperature door position that diverts the appropriate amount of air past the heater core in order to achieve the desired temperature:

- Sunload

- Duct temperatures

- Ambient temperature

- Inside temperature

The A/C system can be engaged by either pressing the A/C switch or during automatic operation. The HVAC control module sends a class 2 message to the PCM for A/C compressor engagement. The PCM will provide a ground for the A/C compressor relay enabling it to close its internal contacts to send battery voltage to the A/C compressor clutch coil. The A/C compressor diode will prevent a voltage spike, resulting from the collapse of the magnetic field of the coil, from entering the vehicle electrical system when the compressor is disengaged.

The following conditions must be met in order for the A/C compressor clutch to turn on:

• The ambient air temperature is above 4°C (40°F).

• The A/C low pressure switch signal circuit is grounded.

• The A/C refrigerant pressure sensor parameter is less than 2957 kPa (429 psi).

• The PCM receives an A/C request from the HVAC control module.

• The engine coolant temperature (ECT) is less than 121°C (250°F).

• The engine RPM is more than 550 RPM.

• The throttle position is less than 100%.

The HVAC control module monitors the A/C low pressure switch signal circuit. If the voltage signal on this circuit has no voltage drop the module will interpret this condition as a low pressure, disabling the A/C request. The A/C low pressure switch will open its internal contacts at 151 kPa (22 psi). Then close the contacts at 275 kPa (40 psi) to resume A/C operation. This switch assists in cycling the A/C compressor and prevents A/C compressor operation if system has a low refrigerant level.

The PCM monitors the A/C refrigerant pressure sensor signal circuit. The voltage signal on this circuit is proportional to the refrigerant pressure inside the A/C high side pressure line. As the pressure inside the line increases, so does the voltage signal. If the pressure is above 2957 kPa (429 psi), the A/C compressor output is disabled. When the pressure lowers to 1578 kPa (229 psi), the PCM enables the compressor to operate.

The sensor information is used by the PCM to determine the following:

• The A/C high side pressure

• An A/C system load on the engine

• An excessive A/C high side pressure

• The heat load at the A/C condenser

Once engaged, the compressor clutch will be disengaged for the following conditions:

• The ambient air temperature is less than 4°C (40°F).

• The throttle position is 100%.

• The A/C low pressure switch is open.

• The A/C high side pressure is more than 2957 kPa (429 psi).

• The A/C low side pressure is less than 151 kPa (22 psi).

• The engine coolant temperature (ECT) is more than 121°C (250°F).

• The engine speed is more than 5500 RPM.

• Transmission shift

• The PCM detects excessive torque load.

• The PCM detects insufficient idle quality.

• The PCM detects a hard launch condition.

[Tim Z]

you guys are scarrin&#39; me. my fans have been working great &#33;

[RedHeartbeat]

I&#39;ve got 40 amp relays but only 30 amp fuses. You need to complain that the high head pressure cutoff switch failed. That is the switch in the back of the compressor and it&#39;s supposed to turn the power off to the clutch if you exceed the head pressure safe for the unit. I built a hi/lo pressure switch into the high pressure line to protect it from excessive pressures. I guess I&#39;ll just put new 30 amp fuses in and see what happens since it&#39;s been this way for about 5 months without problems.

[Chevy366]

No did not use fuses , figured with the fans that it would blow fuses like wild , but I did see from that custom wire place in Ft Worth that they use a buss fuse probably 40 amp or so , in line in the power source line only not to each fan .
Wonder if there is a way to hook up some kind of idiot light (nothing intended) that would show if fans are working or not , so a person would know if they had gone out or not turning on ?

[hummertech]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 18 2006, 02&#58;33 PM) [snapback]58332[/snapback]</div>

Anyone running fuses in their 2005 fans? My 30 amp fuses weren&#39;t enough. How big of a fuse do we need to run? My A/C don&#39;t work without the fans in stop and go traffic. It gets pretty hot running the heater to cool the engine in 105 degree weather too. I&#39;m thinking about going to a thermal breaker so I don&#39;t get stranded without electric fans the next time they overheat.
[/b]

Cooling Fan Control - Two Fan System
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

Important: The right and left cooling fan connectors are interchangeable. When servicing the fans be sure that the connectors are plugged into the correct fan.

The PCM commands the low speed cooling fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 94.5°C (202°F).

• A/C refrigerant pressure exceeds 1447 kPa (210 psi).

• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.

The PCM commands the high speed fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 104.25°C (220°F).

• A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).

• When certain DTCs set.

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.

use 40 amp fuses to each fan, and use 40/50 amp relays. also in a circut that draws that much current the voltage drop across a connector becomes an issue. if you have small wire/bad butt connectors/bad grounds/and things like that the conection points use up voltage in the circut. so when voltage drops, current goes up. check to see is the fans are using the voltage by taking a digatal volt meeter, on dc volts, put the positive lead on the positive wire at the fan, take the negative lead of the meeter and put it on the negative lead at the fan. run the engine, turn the fans on and take a reading on the meeter. it should be no less then 1.0 volt less than system voltgage. if say the fans are using only 10 volts than the wiring is using up the other 4... 40 amp draw at 14.0v works. at 10 volts it doesnt. it will blow the fuse

[Chevy366]

Oh man , where were you at six months ago . K.I.S.S. (keep it simple stupid), now I have to rewire .
Looks as if they used 2 SPST always open relays and the one DPST always closed relay in the middle and probably PCB type .

[GMCwantsLS1]

Mine use fuseable links, not sure what size. They were part of the 1997 f-body fuse/relay junction I used.

EDIT: Sorry mine is the f-body fans not truck fans

[hummertech]

<div class='quotetop'>QUOTE(GMCwantsLS1 &#064; Jul 19 2006, 05&#58;43 AM) [snapback]58364[/snapback]</div>

Mine use fuseable links, not sure what size. They were part of the 1997 f-body fuse/relay junction I used.

EDIT: Sorry mine is the f-body fans not truck fans
[/b]

the f-body fans are wired the same except they use one big ass fuse link insted of fuses, only until 1997, then they found out the fuse link poped when the fan slowed down and people couldnt find the fuse link to repair the it. or repaired it incorrectly. so they started using one 40 amp fuse in 1998 for both fans. the car fans draw less than the trucks. i see f-cars in all the time w/fuse links repaired w/regular wire or too big of fuse link. i guess the replacable fuse takes the stupid factor out of it. i never liked the fuse link.