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Discussion Starter #1
2002 Maserati GT Spyder

I spent some time reading as much as I could in regards to this issue i am having. Most were general answers for beginner diagnosis. So far here is what i have done:

AC evac and vacuum tested to -30 psi for 30 minutes no leaks
Refilled with 750g R134
AC compressor comes on and pressure readings are good
Blower fan works as intended and has strong flow
reset the AC system using reset procedure
Vents blow ambient temperature air
Turning temp control knob to full heat activates the heater and is hot air
Turning temp control to full cold blows ambient temperature air.
Exterior ambient temp sensor reads correctly on dash
Setting controls to AUTO for both fan and setting makes no difference from setting them to manual for vent and cold.

Feeling a little frustrated at this point I am reaching out to see if anyone has had issues with the following hypothesis I a have:

1. Interior temperature sensor failure located on the left side of the steering wheel?
2. Heat/AC mixture flap failure inside the evaporator box not closing or opening?
3. Possibly rotary knob reading heat cycle properly but not the cold cycle?

Many thanks in advance for any direction. If I screwed up posting (location or procedure) I apologize as I have read posts hundreds of times but hardly ever have posted before.
 

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Discussion Starter #3
First, thank you for the response. I followed the procedure and AA came up first followed by OO indicating no codes.
 

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Tony H.

The distribution knob is set at automatic and works properly. When I switch to any of the other cycles (defrost, etc...) it functions properly. The issue at hand is only one and that is that there is no cold chilled air just lukewarm. Cycling the temperature knob to full hot functions properly and blows very hot air. Turning it counterclockwise to max cold, it simply blows ambient lukewarm air. This mixing actuator I assume is located behind the kick panel on the drivers side?
 

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Tony H.

The distribution knob is set at automatic and works properly. When I switch to any of the other cycles (defrost, etc...) it functions properly. The issue at hand is only one and that is that there is no cold chilled air just lukewarm. Cycling the temperature knob to full hot functions properly and blows very hot air. Turning it counterclockwise to max cold, it simply blows ambient lukewarm air. This mixing actuator I assume is located behind the kick panel on the drivers side?
From what you've just said find the low pressure line in the engine compartment. Item 9 on table 144 in the link I sent you. It should be cold to the touch when the AC is running. You said earlier the pressures were good but I just want to confirm that your AC system is actually cooling. If that checks out the actuator is on the right side of the tunnel, same side as fan.

P.S. Should read table 145 and touch the metal tubing.
 

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Discussion Starter #8
I feel naive not having checked the low pressure line and took the gauge readings for granted. No cold flow on the low pressure side.
 

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Glad you found your problem. Like everyone, I had forgotten the easy and obvious check to start with. With engine shut off you should measure about 60 psi at the cold port. When the AC is on the cold port pressure should be around 25 psi and the high side 300 to 400 psi.
 

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Just curious if you've come up with a fix now that you've identified the issue. I'm having a similar problem. One issue I've got with this car is that the engine sounds so loud in my garage that I can't hear if the AC compressor is actually on.
 

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I had this same problem in my f355 ferrari. Look and check diagrams to see if theres a HEATER CONTROL VALVE. If a heater valve is not working correctly you will not get cold air. Also look and see if theres a AC ECU. If there is an AC ECU it controls everything related to heat and AC. In my situation the AC ECU had a bad chip in it so it wouldnt let the heater control valve open or close. When working correctly when you turn your switch on for the AC and move the dial to cold, the heater valve closes and stops the flow of hot water thru the system. This plays a part on the ac blowing cold ac.....Im not sure if this will apply to your issue but it my be worth looking at if you cant find anything else...Hope this helps.
 

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This post helps a lot but let me share with you guys , to help as many ppl as possible,
I start to have the same issue, A/C not getting cold no matter how I turn the KNOB! Right Cold left Hot.
After getting tired I had idea to put my girls hair dryer blowing hot air at the Passenger Temperature Sensor, (Right side of steering whell).
And guess what, A/C start to BLOW COLD AIR AGAIN.
So I'll order the part and probably my problem is SOLVED
Maserati 385500199, PASSENGER COMPARTMENT TEMPERATURE SENSOR - Scuderia Car Parts (385500199) PASSENGER COMPARTMENT TEMPERATURE SENSOR
Best of luck to anyone
 
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