Itsmejoe231

I am changing out the liquid line on my 99 and want to replace the orifice while I am in there, but cannot fint the old orifice.

Can anyone tell me where it's at?

kawi600

Its inside the hvac unit behind the dash, inside the liquid line. You can get this as one piece and its not too expensive. Id replace everything in there if youre doing this one thing though. Heater core, condenser, liquid line and maybe the blower motor. Its a big job to get in there.

vzdude

The orifice tube is inside the condensor. Cant' remember which line for sure, IIRC its the line coming up from the bottom that angles up. Should be about 3 bucks at any parts store.

I PASS GAS

Not sure why all the varying replies, but on my 01 it was in the liquid line. If you look closely at the liquid line as it makes that straight run right up against the fender, there is a crimp on each side of the orifice. You can also hear it equalize after you shut the truck off right there at that point. Definately a metering device in there.

Itsmejoe231

I called the dealership and asked them. They say it is built in to the liquid line. Could be why I did not find the old one. So why do the parts stores sell a replacement orifice when you have to replace the liquid line?

Something still dont add up yet.

I dont want to have to take my dash out to replace all that other stuff unless something else is broke...Lets hope nothing else is broke.

Thanks for all the help!

vzdude

My bad ! The older trucks it was mounted in the condenser tube. Work fine on them! Why change? Here's an excerpt from the FSM.


FIXED ORIFICE TUBE
The fixed orifice tube is located in the liquid line, between the condenser and the evaporator coil. The orifice has filter screens on the inlet and outlet ends of the tube body. If the fixed orifice tube is faulty or plugged, the liquid line assembly must be replaced. See Liquid Line in the Removal and Installation section of this group for the service procedures.

058hamer

so it is normal to here a hissing noise when you shut off truck? i had to recharge mine 6 or 7 weeks ago heard the hiss and thought i had a leak bet its still working tnx 058hamer

Itsmejoe231

Another quick question for you guys...

At what pressure is the low pressure switch supposed to cut the commpressor off?

My pressure on the low side got down to about 5lbs and it never cut out. When I got 2lbs of 135a in the line froze. It freezes up regularly going down the highway and I have to switch the selector to vent for about a mile then put the ac back on before it will cool off. I think the low pressure switch is not working and letting the pressure get to low and the line freezes.

Any comment?

vzdude

low side switch.....should be around 20 psi- 25 psi. I'll see if I can get the exact info and will post later.

jrs_dodge_diesel

Yes, completely normal. Basically you have around 225 PSI (depending on ambient temeratures) in the hi side, and 35 PSI (again depending on ambient temps) in your low side lines. When you shut off the truck, the compressor stops too. With nothing to maintain that high pressure on the hi side it slowly equalizes over to the low side, via the orifice tube.

jrs_dodge_diesel

Don't know exactly on the pressure for the switch but normally, the main function of that switch is to protect the compressor from grenading, due to refrigerant loss.

When you say you put 2lbs in, was the system vacuumed down prior to you charging it? If not, you have a strong possibility of moisture intrusion. Moisture doesn't compress much, can freeze in the lines, and also react with the refrigerant and turn acidic (very corrosive).

Itsmejoe231

I called the dealer tech and he told me the low pressure switch was actually a temperature switch. It cuts off the compressor at 35*.

When I put the 2 lbs in it had a vacuum on the system.

Now that I have replaced the switch, the inside cab air temp only gets to 60 degrees. Which is not very cool compared to my buddy's CTD. The compressor cycles on and off quite frequently, my pressures on the AC gauges are OK but it will cycle on and off before it has time to build any good pressure.