My son's truck, 1984 F150 with 4.9L needs the following:

1. Instrument Cluster Voltage Regulator [I believe from prior thread, you provided that the correct Ford number is D1AZ10804A or Motorcraft GR513]. Is that correct?

2. The vacuum selector switch which directs the defroster/vent/AC/heater air flow. It is equiped with factory A/C. I have traced and replaced vacuum lines, checked the one-way check valve, connections, etc., but it still defaults to defrost mode when accelerating or going uphill. I cannot hear a leak, but feel that being plastic and 25 years old, the selector switch is the likely source. I cannot see any cracks in the vacuum reservoir and when the vacuum line is removed, there is a strong hiss as the air rushes in. What is the best way to test the reservoir?

Thank you in advance for your assistance and for routinely sharing your experience with all of us.

 

[quote What is the best way to test the reservoir?[/quote]


I am sure that Bill will respond to your request and not trying to steal his thunder but obviously you do have a vacuum leak and they can be hard to find. Since you have been so thourgh in replacing lines, etc you would do well to invest in a hand vacuum pump with a guage such as this:

http://www.harborfreight.com/cpi/cta...emnumber=92474

This pump will allow you to pull a vacuum on any devise, ie reservor, vacuum lines, actuators, a/c heater control head and has a guage to determine if that devise is leaking down. Hope this helps you.

 

Thank you for the prompt and very informative reply, redlightning93. The vacuum pump is so affordable. I will add one to my set of tools.

 

Bill will need to know if the truck has dual tanks as well, as the Fuel Tank selector switch is bolted to the heater-A/C control panel on the right side, if equipped.

 

Thanks, 81-F-150-Explorer!

It has one tank. It is a short wheel base with the approximately 16 gallon tank.

 

D1AZ10804A .. ICVR = Instrument Cluster Voltage Regulator (Motorcraft GR513) / Available from Ford.

MSRP: $78.36 // FTE sponsor Y2KFORDPARTS.COM price: $42.31.

Fits: 1971/86 F100/350 / 1971/90 Econoline / 1978/86 Bronco / Myriad 1971/79 Passenger Cars.
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E1AZ19B888B .. A/C Vacuum Control Selector Switch & Valve Assy (Motorcraft YH380)

Fits: 1983/91 F100/350 & F(Super Duty) / 1983/91 Bronco / 1981/91 Crown Vic/Mercury Grand Marquis w/o ATC / Available from Ford.

MSRP: $26.98 // Y2KFORDPARTS.COM price: $15.64.

This valve bolts to the rear of the A/C-Heater Control Panel. All the vacuum lines connect to it.
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E3SZ19A566B .. A/C Vacuum Reservoir Tank & Bracket Assy / Available from Ford

MSRP: $28.98 // Y2KFORDPARTS.COM price: $20.87.

Fits: 1983/93 F100/350 & F(Super Duty) / 1983/93 Bronco / 1983/90 Econoline / Myriad 1983/92 Passenger Cars.

Y2K aka PARTSGUYED.COM = MILLENNIUM FORD in Seattle WA

 

Thank you, NumberDummy.

 

Okay, a little bit of an update, regarding the vacuum leak in the AC of my son's 1984 F-150 with 4.9L engine. By the way, my son serves our great country in the ARMY, so we work on his truck together when he is on leave, which explains the time gap from the original post. I removed the cover plate over the radio to gain access to the vacuum control valve as well as being able to see the vacuum lines and servo motors. Near the top of the dash, where the mono radio speaker normally resides, was a servo motor with two ports. I noticed the vacuum line for the top port was not attached. I found the vacuum line in with wires, etc. The rubber connector was in good shape. I then asked my son when he first noticed the AC problem and he replied that it was in the spring. I asked when he had the new aftermarket stereo system installed? It was installed last December. Apparantly, during the stereo intallation, someone had accidently dislodged the vacuum line. By the way, for those who might ask why the normal vacuum hissing sound was not noticed? The plastic vacuum lines are very small in diameter. Anyway, we buttoned everything back up and when he next drove on the highway and passed vehicles and climbed up hills, the AC functioned as it should without defaulting to the defrost mode as before.

Isn't it great to drive something which actually can be repaired! Thanks again to everyone for the valuable input!