If you buy a kit with dash unit it will be setup for r134. When using r134 for best cooling in city or stop & go driving it's best to use a electric fan and install the condenser to 1/4-3/8" to the radiator for max air flow being pulled through.

Or switch to a smaller water pump pulley to get more air moving through the rad and the use of a fan shroud. If not then your cooling system will blow warm & cool with city driving.
Do lots of reading before you jump into this for a better understanding.

Orich

 

These older trucks not having a clutch fan might cool things okay? I know my '89 has a clutch fan and it is horrible sitting still with 134a in it.

The underdash unit I put in my Mack has a separate fan on the condensor and it will freeze you out sitting still with 134a in it.

 

And for this reason, I'm still running r12 with the smaller 5cylinder 507 Sanden compressor. One important fact about fan clutches. Is if it's an add on fan clutch make sure it's for the AC fan clutch must be used. As it's less free spinning then the non AC fan clutch. And make sure to use the matching size Pullies also.

Orich

 

It's all factory installed, so I'm guessing it is all correct. Don't think anything has been touched on it before I bought the truck. Only had 80K miles on it then, 170K now and I have not replaced the clutch fan.

Was adding some freon the other night(won't hold a charge all summer), it was 80+ degrees and the fan was hardly pulling any air and my pressures were spiking. I'd have to rev'r up some to get some air moving and then the pressures would drop back down.

 

Sounds like you better buy a GOOD fan clutch. With that fan not pulling enough air through the condenser the Freon can't release the heat it's picked up. The system pressure rises because Freon BOILS at a temp below water's freezing point. R12 and R134a anyways.


<table width="562" border="0" cellspacing="2" cellpadding="5"><tbody><tr><td height="30" align="center" class="body-grey1" valign="bottom" colspan="4"> </td><td height="30" align="center" class="body-grey1" valign="bottom"> </td></tr><tr><td height="30" align="center" class="body-grey1B" valign="middle" bgcolor="#dce4e1" colspan="4">



</td><td class="body-grey1B" bgcolor="#e3e3e3">Boiling Points


</td></tr><tr id="123_neoTD3" style="background-color: rgb(255, 255, 255);"><td height="20" align="center" class="body-grey1" bgcolor="#e8eeeb">


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">R-12


</td><td height="20" class="body-grey1" bgcolor="#e8eeeb">Dichlorodifluoromethane


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">CCI2F2


</td><td height="20" class="body-grey1" bgcolor="#e9e9e9">-21.6°F


</td></tr><tr id="123_neoTD3" style="background-color: rgb(255, 255, 255);"><td height="20" align="center" class="body-grey1" bgcolor="#e8eeeb">


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">R-22


</td><td height="20" class="body-grey1" bgcolor="#e8eeeb">Chlorodifluoromethane


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">CHCI F2


</td><td height="20" class="body-grey1" bgcolor="#e9e9e9">-41.5°F


</td></tr><tr id="123_neoTD3" style="background-color: rgb(255, 255, 255);"><td height="20" align="center" class="body-grey1" bgcolor="#e8eeeb">


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">R-114


</td><td height="20" class="body-grey1" bgcolor="#e8eeeb">Dichlorotetrafluoroethane


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">CCIF2CCIF2


</td><td height="20" class="body-grey1" bgcolor="#e9e9e9">38.6°F


</td></tr><tr id="123_neoTD3" style="background-color: rgb(255, 255, 255);"><td height="20" align="center" class="body-grey1" bgcolor="#e8eeeb">


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">R-134a


</td><td height="20" class="body-grey1" bgcolor="#e8eeeb">Tetrafluoroethane


</td><td height="20" class="body-grey1" bgcolor="#e4ebe8">CF3CH2F


</td><td height="20" class="body-grey1" bgcolor="#e9e9e9">-15.1°F


</td></tr></tbody></table>

 

Also don't know if you know to set the rpm up to 1200-1500 sucks in the Freon faster plus helps keep the PSI down. You

It's been 6-7 yrs since installing the little 5cyl. Sanden 507 compressor my system holds 28oz. r12 Freon.

Orich