Would the heater control module cause the compressor to stay on even though I select heat?

Which of these two systems does your truck have?

Electronic Automatic Temperature Control (EATC) System
Or
Electronic Manual Temperature Control (EMTC) System


Electronic Manual Temperature Control (EMTC) System
The electronic manual temperature control (EMTC) system heats or cools the vehicle depending on the EMTC control panel selection.

• The EMTC control panel selections determine heating or cooling, air distribution and enables blower motor operation.
• The temperature control setting determines the air temperature.
• The blower motor switch varies the blower motor speed.
• During A/C operation the system also reduces the relative humidity of the air.

The EMTC system operation is determined by the settings on the climate control module. The EMTC system is composed of the EMTC module, blower motor resistor, mode door actuator, air inlet door actuator and temperature blend door actuator to control the various functions.
The blower motor switch:

• sets the blower motor speed.
• directs the blower motor path to ground through the blower motor resistor to allow blower motor operation in LO, MED LO and MED HI.
• directs the blower motor path directly to ground, bypassing the blower motor resistor, to allow blower motor operation in HI.

The A/C request button:

• can command the A/C compressor ON when the function selector switch is in PANEL, FLOOR/PANEL, FLOOR/DEFROST and FLOOR when the A/C request switch is pressed. Indicator illuminates when A/C request switch is toggled ON.
• is inoperative in MAX A/C, OFF and DEFROST.
• indicator illuminates when the function selector switch is in MAX A/C and cannot be toggled.
• indicator does not illuminate in OFF and cannot be toggled.
• indicator does not illuminate in DEFROST but can be toggled ON or OFF. The A/C compressor will operate regardless of indicator status if the outside air temperature is above 6°C (43°F).
• is serviced only with the EMTC module.

The function selector:

• selects airflow direction.
• is serviced only with the EMTC module.

The temperature selector:

• selects full warm and full cool as well as blended outlet temperatures.

The air recirculation button:

• selects either recirculated or outside air source.
• recirculates air in any mode except DEFROST, if requested.
• is disabled in MAX A/C or OFF mode where recirculated air only is used.
• is disabled in DEFROST mode where outside air only is used.
• is serviced only with the EMTC module.

The EMTC module also includes:

• a heated mirrior button. Refer to Section 501-09 .
• heated seat controls. Refer to Section 501-10 .

no
adding gas with out using the proper gauges to get the correct pressures results in excessive head pressure and eventual compressor failure
the over pressure switch has probably switched off the compressor to prevent that failure
The original problem most likely is a problem climate control module that set the heater to full heat thereby overcoming the cold air from the ac
What will help now is to have the ac system properly diagnosed by an accredited ac specialist shop as well as having the climate control module checked for correct operation

First check your coolant level. If the coolant system is full, then it is probably the passage doors inside the heater/AC case not operating properly. A door or its actuator has a malfunction. Most actuators are vacuum controls, although some are electric motor operated. Turn Heater on and set temp. control on high-this should cause the actuators to respond by opening some inner doors. So when you turn the blower on, air is forced across the heater core (the little coolant filled "radiator" in the case), and warm air comes out the vents. Watch or listen for the actuators to respond when you use the heater controls. There may be several actuators on the heater case, situated all around, but they are on the outside of the case, right near the inner door they operate.

This is related to communication with the transmission shift "range selector". It is a loose connection that is causing the control module to "see" a park or Neutral and the doors unlock. This may turn on the check engine light also. It may eventuallly cause the transmission to not shift, also. You need to check the connection on the transmission and on the shift range selector (sometimes called the "PRNDL" switch. The computer automatically locks the doors when you select a gear. It is seeing no gear selected and unlocking the doors, the seeing a gear selected again, and locking the doors. You really need to get this repaired soon.

Sounds like a problem with the selector switch or the HVAC control module, or the PCM.
The PCM thru the control module grounds the compressor relay when the compressor is needed.

did you burp the system after you where done. The heater d-core is the highest place in the cooling system and will be the first to collect an air pocket. Running the vehicle at idle with the cap off will help purge the air out.

The a/c will turn on any time the mode switch is on defrost. When the heat selector is turned to hot the air will first go through the a/c evaporator core and then through the heater core. When the heat selector is turned to cold air will only go through the evap core. So regardless if the a/c compressor is on or not with the heat selector on hot it should blow hot air.

Did the heat work before you replaced the other parts?

If not than it is possible that the heater core is plugged. Especially if the coolant was really dirty before you started.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

there is a selector motor on the side of the heat ac coil box under the dash. it should have 2 or 3 levers on the side of it. it controls the dampeners the select where your air is moving to from the defrost to the bi level to the floor or all of the above find that control module and then turn the car on and start moving the selector switch back and forth slowly while watching that module if its moving the levers then you have a more serious problem and need to have a professional look at it. check to make sure that the levers are even connected and that the wiring harness is even hooked to the control module

my dad had the same problem in his 95 ford ranger it ended up being the control module that selected heating and colling and what vent postion the steper motor should select
you can buypass the module under the hood so it isnt kicking in the ac when you want heat
but ultimatly have the dealer fix it since its a factory defect :) cheers hope this helped

ok could be one of 3 things. 1 you may be out of freon. (proly spelt that wrong) 2. compresser could be bad. 3 the clutch on your compresser might not be engaging. when trucks running turn ac on and see if the front of your compresser spins or not. if it does clutch is good. but it could be that your compresser is still bad. either way i recomend you go for freon and start there. when they fill it they will tell you for sure wether or not your compresser is bad.

there could be an air lock in the system, pluged heator core, a bad thermostate or control modual. try bleeding the air out through the bleeder screew if there is no heat after that have the control modual tested if its okay try having the cooling system flushed then if it still doesnt heat intall new termostate