AC blowing hot air only

HERRSERVO

MEMBER
2006 FORD FUSION
2.3L
4 CYL
2WD
AUTOMATIC
150,000 MILES

Had it checked at a shop. Freon is full. Compressor not kicking on. Checked climate control fuses under dash, all fine. Checked AC related fuse and relay under hood, both fine. Mechanic said it is something electrical/wiring related. He removed relay and jumped it off with whatever tool you would do that with and the compressor kicks on and AC blasts cold air. So something is not allowing power to get to or pass through the relay to the compressor.

Before I replace the climate control unit is (are) there anything(s) I should troubleshoot first?

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi and thanks for using 2CarPros. Com.

Has the high pressure transducer switch been checked?
The A/C high pressure switch is used for additional A/C system pressure control. The A/C high pressure switch is either dual function for multiple speed, relay controlled electric fan applications, or single function for all others. If pressure is too high or low, it results in the A/C turning off, preventing the A/C pressure from rising to a level that would open the A/C high pressure relief valve. I attached two pictures. First is the location (best I could find, sorry) and the second is a picture of the connector and what each wire is for.

Also, here is a link that discusses different reasons why an AC may not be working. If you page through it, you'll come to the section that discusses the pressure switch I mentioned. Also, and very important, it discusses static pressure. That is the pressure in the system when the compressor is not on and the engine is off. Static pressure that is too high or low will cause the system to not run. If it has not been checked, do that.

Take a look at this and let me know what you find. I hope something here helps.

Take care,
Joe.

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Saturday, September 29th, 2018 AT 7:19 PM

HERRSERVO

MEMBER
3 POSTS

Thanks for the information Joe. I will check into it in the next few days. Just out of curiosity, without a check engine code showing, can you run a system diagnostics check and determine the specific cause for this? I am all for the troubleshooting process as I do love digging around an engine but I do not have much extra time or money for that right now, so I would much rather just know exactly what it is and fix it. Fixing stuff is easy for me. Figuring out what exactly is wrong, not so much.

I read something about the EVAP Discharge Air Temperature Sensor and how Ford Fusions are known to have problems with them. And (more importantly) how they require the removal of half of the interior of the car? Aka dash, console, trim, etc, to get to. I would very much hate to go through that entire process in troubleshooting mode only to find out that it was not the culprit, even though it is a $20.00 part and would save upwards of $1,000.00 in labor.

Anyway thanks for your help brother!

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Sunday, September 30th, 2018 AT 4:52 AM

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

As far as a trouble code, chances are no. What often happens if a sensor malfunctions is it sends the wrong signal. The computer (being a computer) has no idea that it's wrong.

The EVAP discharge temperature sensor can be an issue. And yes, a pain to get to. I have attached a picture of its location. The directions listed below are what is provided. They left the difficult parts out. And yes, half the car has to come apart.

Here is a definition of the component:

EVAPORATOR DISCHARGE AIR TEMPERATURE SENSOR

The evaporator discharge air temperature sensor contains a thermistor which receives a reference voltage from the PCM. The thermistor then varies the resistance to the reference voltage based on the evaporator discharge air temperature. The resulting voltage is returned to the PCM where it is interpreted as an evaporator air discharge temperature reading.

The PCM maintains evaporator core temperature and prevents icing of the evaporator core, by disengaging the A/C compressor clutch when the evaporator discharge air temperature sensor reading falls below acceptable levels, and by engaging the A/C compressor clutch when the discharge air temperature rises above acceptable levels.

The evaporator discharge air temperature sensor is located inside of the heater core and evaporator core housing in the air-stream leaving the evaporator core.

_______________________

Removal and Installation

1. Remove the instrument panel. Please refer to: Body and Frame, Interior Moulding/Trim, Dashboard/Instrument Panel. See: Dashboard / Instrument Panel > Removal and Replacement > Instrument Panel - Exploded View
2. Detach the A/C evaporator discharge air temperature sensor.
3. Disconnect the A/C evaporator discharge air temperature sensor electrical connector.
4. Remove the evaporator discharge air temperature sensor.
5. To install, reverse the removal procedure.

______________________________

The last 6 pictures show how the instrument panel comes apart. I thought I would add them just in case you decide to give it a try.

Let me know if any of this helps. Also, if you could provide the static pressure readings of the system, it may prove beneficial.

Let me know.

Joe

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