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Andy, Truck Diagnostic Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 1648
Experience:  International and Isuzu trucks , International, Maxxforce, Cummins and Isuzu engines, Diagnostic and electrical troubleshooting specialist , Hvac and truck /trailer refrigeration troubleshooter
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Sorry, I hit the wrong button earlier and closed out my

Customer Question

Sorry, I hit the wrong button earlier and closed out my window before entering credit card info. Do you have mechanics that are knowledgeable about big trucks?
JA: What is the make/model/year of your car?
Customer: 2009 International 7600 Workstar
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: I have a mechanic that works on my trucks, but he is unable to figure this one out.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Yes, AC is not working. Freon level/pressures are good. AC compressor, thermosisters, expansion valve, dryer, heater core, condensor, control knobs, and resistor block have all been changed in the last month.
JA: Have you checked the coolant level? Has there been any leaking from the hoses?
Customer: Yes, freon level is good, no leaks.
Submitted: 11 months ago.
Category: Medium and Heavy Trucks
Expert:  Andy replied 11 months ago.

Hi there ! My name is ***** ***** Can we start with the last 8 digits of the vin number please ?

Customer: replied 11 months ago.
Expert:  Andy replied 11 months ago.

Thank you ! I'd like to start by retrieving the body controller fault codes . Please follow this procedure :

Customer: replied 11 months ago.
I will have to go through this process when the truck arrives back at our shop this evening. I'll report back in the morning.
Expert:  Andy replied 11 months ago.

ok I work days so will respond later in the day

Customer: replied 11 months ago.
#1: SPN 611 FMI: 14;
#2 SPN 789 FMI 2;
#3 SPN 3697 FMI 5;
#4 SPN 3981 FMI 2;
#5 (Inactive) SPN 84 FMI 2
#6 (Inactive) FMI 101 SPN 2
Expert:  Andy replied 11 months ago.

Wow ! This is a tall list ! I can look all this up for and send troubleshooting if needed but I think we would be better to do this over skype

Customer: replied 11 months ago.
I don't skype, but we can do it over the phone. I know a few of the codes to be an ABS, and one to do with DPF filter, which is a sensor problem, but the rest I don't. As for the AC problem. I'll give you a rundown of what's been done. Everything AC wise has been replaced, including the condenser, compressor, dryer, thermasisters, expansion valve, heater core, resistor block on side of blower motor, control knobs, and one blend door motor. AC will work fine for a while, then start freezing over, as it will start to blow warm moist air through the vents. It can be turned off for a few minutes and then turned on and it will go back to working for several more hours. On occasion it will stop blowing cold air all together and just blow hot air w/ the compressor cycling every couple of seconds. The Freon levels have been checked and pressures checked and changed, and no difference in performance.
Expert:  Andy replied 11 months ago.

Can you tell me what position the ac is in when this happens ? In max ac mode or normal ac ?

Expert:  Andy replied 11 months ago.

Also , has anyone checked the HVAC filter located in the fresh air intake ? If it is fairly plugged , what happens is the air flow accross the evaporator inside while be restricted too much resulting in the evaporator eventually freeing over .

Expert:  Andy replied 11 months ago.

If you look where the wiper arms are in the cowl , on the passenger side of the truck , you will find the fresh air intake for the hvac system . Key on , making sure the AC is set to normal ac mode , look down into the intake and you will see the filter in there .

Customer: replied 11 months ago.
I've replaced that one a couple of times making sure that wasn't the problem. If we run on Max it freezes much faster and more often, so he runs it on Norm all the tim with periodic freezing
Expert:  Andy replied 11 months ago.

Ok , have we checked the filters inside for the max ac function ? They may be plugged !They never get looked at .Also exactly how much freon was put in the system ?

Customer: replied 11 months ago.
I don't know where the max filters are, and didn't know there was such a thing. As for the amount of freon I'll have to check with my mechanic in the morning.
Expert:  Andy replied 11 months ago.

Ok .. .sounds good ! I work days so will check in with you tomorrow night if thats ok ! The recirc filters are located inside the cab on the passenger side . They are blue in color and there is one on either side of the hvac unit below the fuse panel . If you pull the right side lower kick panel , you will see one of them right by the resistor pack that was replaced . Just above it . The other one is facing the doghouse cover .

Customer: replied 11 months ago.
Good deal, I'll check those out this afternoon when he gets in, and get with you on the freon level as well.
Customer: replied 11 months ago.
My mechanic told me that it has appx. 2.5 lbs of freon in it. He said he has played around with different levels to see if the pressures would change or work better, but same results.
Expert:  Andy replied 10 months ago.

I just checked the spec on that particular model and it is supposed to have 36 ounces or 2.25 lbs in the system . Have you checked the recirculation filters inside yet ? They are likely plugged if freezing up especially in max ac mode

Customer: replied 10 months ago.
I've had my mechanic working on more pressing issues lately, but I believe he is planning to take a look tonight. I've looked up in the area you spoke about and didn't see them, so I'm assuming you have to open up the ac box to get to them.

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