R12 System Not Cold

[Joes4x4Ranger]

I have a 91 splorer. Had a botched R12-R134a retro that puked the compressor. Replaced compressor, drier, orifice tube, flushed system, added 8oz mineral oil, pulled 5 micron vacuum for 1 hr, weighed in 32oz of R12.

Our ambiant's have been 106*-119* since the above was done, I cannot get the center vent temp below 50* at idle it's around 65*. That sucks big time for an R12 system. My accumulator and suction lines are not "cold" either.

I think my fan clutch is shot. I will replace it next week. Will a heater bypass make much difference in the output air temp? Would the heat from the heater core warm the evaporator or just the output air?

I also used a variable orifice tube from Autozone. Should I recover the R12 and put a standard tube back in it??????(They where out of the standards so I got the variable)

 

[Joes4x4Ranger]

Nobody has a clue??????????

 

[ranger7ltr]

I would help if you posted your high/low pressures...

I personally have not had real good luck using the variable orifice tubes on R12 systems but then I didn't have a questionable cooling system fan either...I would assume that you vacuumed the system long enough to remove all traces of moisture and air and the pressures are close to the correct ranges...With ambient between 106-119f you should probably be seeing 265-300 psi high side...Anything much lower than that and either the compressor is not working or the variable orifice tube is not helping your system...

I would run the engine with the a/c on and then cool the condensor with a garden hose and see if the vent temp drop appreciably...You can also see if the pressures drop as well..

If they do, i would change that fan clutch and check the radiator for dirt in the fins or any other obstructions stopping air from passing through...And I don't remember if the heater core is in the same compartment as the evaporator but you can squeeze off the coolant flow with a pair of vise grips and see if that has any effect...

 

[Joes4x4Ranger]

At idle LOW= 45-50 HIGH 350

At 1500 RPM LOW 45 High 325

Running water on condenser @ 1500RPM LOW 35-40 HIGH 275

Running water gets the center vent temp to 45* Why is it not cooling at 50-60 mph???? At those speeds the radiator fan should have no effect. I blew out radiator fins then washed them out with water before re-charging system.

The system pressures indicate slight over charge, but the system calls for 32oz of R12, I even verified this with Ford. The refrigerant was weighed in with a very accurate charging scale. I even weighed the cylinder on a digital mail scale before and after charging to be 100% sure.

Could that freaking variable tube be creating the higher pressures???

 

[ranger7ltr]

Do you have a way to capture some of the R-12 charge?

I was thinking the system pressures show an overcharge and the variable orifice tube might have a problem with it... I would get the high side down to 275-300 MAX @ 100F ambient and see what the system does for you...

One item I didn't ask about was the condensor...Are you using a new OEM style condensor or is it a new updated serpentine style similar to the later model trucks? I am wondering if the condensor is a serpentine style the factory capacity will be off since that style of condensor will hold more refrigerant...

And were you able to verify the fan clutch function? I know the ram air effect while driving should sufficiently cool the condensor and radiator so the fan clutch function would have more of an effect at idle and lower speed but if it is marginal or not effective that is just more heat the system has to deal with once you get moving...

 

[Joes4x4Ranger]

I was thinking the system pressures show an overcharge and the variable orifice tube might have a problem with it... I would get the high side down to 275-300 MAX @ 100F ambient and see what the system does for you...

One item I didn't ask about was the condensor...Are you using a new OEM style condensor or is it a new updated serpentine style similar to the later model trucks? I am wondering if the condensor is a serpentine style the factory capacity will be off since that style of condensor will hold more refrigerant...

And were you able to verify the fan clutch function? I know the ram air effect while driving should sufficiently cool the condensor and radiator so the fan clutch function would have more of an effect at idle and lower speed but if it is marginal or not effective that is just more heat the system has to deal with once you get moving...

The condenser and evaporator are factory 91, I just flushed them out real good. The fan clutch is not working, it roars for a few seconds and then wont hold a piece of cardboard to the grill.

I'll recheck pressures after I get a good fan.

 

[Glacier991]

After all this time I have to go back and edit my sticky. I said 32 OZ of R-12, which is wrong, It should be 28 OZ. IF you got your 32 OZ from my thread I aologize. I am betting your overcharge, plus your weak fan possibly coupled with a weak compressor may explain your problem. Other answers, a bad or leaky heater door can allow hot air to mix with the incoming air effecting cooling. What is your low side pressure? I am betting around 50. If you can recover 4 oz, you may see improved cooling, if, after that and a new fan clutch you still have problems, it could be an overly weak compressor, or a leaky heater door.

 

[Joes4x4Ranger]

After all this time I have to go back and edit my sticky. I said 32 OZ of R-12, which is wrong, It should be 28 OZ. IF you got your 32 OZ from my thread I aologize. I am betting your overcharge, plus your weak fan possibly coupled with a weak compressor may explain your problem. Other answers, a bad or leaky heater door can allow hot air to mix with the incoming air effecting cooling. What is your low side pressure? I am betting around 50. If you can recover 4 oz, you may see improved cooling, if, after that and a new fan clutch you still have problems, it could be an overly weak compressor, or a leaky heater door.

Glacier,
My Haynes shows 32oz, R-12 and I even called my local Ford dealer to see what they call for, 32oz R12 1993 and earlier. Just for ***** and grins I did recover 4oz, no difference in vent temp. New fan clutch today, no difference in vent temp.

I think I fuked up putting that variable orifice tube in my R-12 system. That tube is designed to restrict flow in a 134a retro. That restricted flow keeps the the refrigerant in the condenser longer and produces more sub-cooled refrigerant.

My theory is the variable tube is producing too much sub-cooled refrigerant in the R-12 system and flooding the evaporator. My pressures are perfect @1500rpm Low 35psi High 280psi ambient 104F center vent temp 54F. Not a lick of difference at 60-65mph still a lousy 55-60F center vent temp.

That vent temp should be 40-45F. I pinned my outdoor blend door shut I have not tried pinching off my heater hoses yet, but I really think the variable tube is the problem.

 

[Joes4x4Ranger]

My theory was wrong, but the tube is the problem, it is just the opposite. The condenser is "Flooded". The variable tube is causing a restriction for sure. I just checked my sub-cooled and super-heat temps. My pressures are normal but I have excessive sub-cool, my condenser shows the temp drop to sub-cooled about 1/2 way down. My super heat temp is 6-7* too high at the suction line leaving the evaporator.

This means not enough refrigerant is flowing into the evaporator. So, the bottom of the evaporator is cold but warms quickly near the top. This is why the pressures look good but the system is not cooling. The evaporator actually needs more liquid in it than the variable tube will allow, R12 is much more effective at transferring heat that R134a.

With 134a higher pressures are required to produce enough sub-cooling, the variable tube helps hold the 134a in the evaporator long enough to sub-cool especially at idle or low air flow speeds.

 

[Joes4x4Ranger]

I recovered my R12 and put the right orifice tube in. NOW I have 42* air @ 60mph with an ambient of 94*.

The technique I used to diagnose the problem is very very rarely used in automotive A/C. I'd say 85-90% of ASE certified A/C tech's don't know how to use a pressure/temp chart. My commercial HVAC experience is what led me to check the sub-cooled/super-heat temps.

BTW Sub-cooled is refrigerant that is cooled PAST its condensation temperature, ie: if at a given pressure R12 condensed at 100F, and the condenser outlet temp was 95F. the liquid would be 5F "sub-cooled".

Super-heat refrigerant has been heated PAST its evaporation temperature. ie: if at a given pressure R12 evaporates at 45F and the evaporator outlet temp is 50F the gas would be 5F "super-heat".

I have a program at work with the math formula and pressure/temperature charts. I've never seen one used in an auto shop.

 

[weston vance]

orifice tube

just wondering how to replace the orifice tube. do i need a special tool ?? thanks

 

[Joes4x4Ranger]

just wondering how to replace the orifice tube. do i need a special tool ?? thanks

I just use a stout pair of needle nose. Grab the end of the tube and pull it out.

 

[ranger7ltr]

Great to know your system's working...

I recovered my R12 and put the right orifice tube in. NOW I have 42* air @ 60mph with an ambient of 94*.

The technique I used to diagnose the problem is very very rarely used in automotive A/C. I'd say 85-90% of ASE certified A/C tech's don't know how to use a pressure/temp chart. My commercial HVAC experience is what led me to check the sub-cooled/super-heat temps.

BTW Sub-cooled is refrigerant that is cooled PAST its condensation temperature, ie: if at a given pressure R12 condensed at 100F, and the condenser outlet temp was 95F. the liquid would be 5F "sub-cooled".

Super-heat refrigerant has been heated PAST its evaporation temperature. ie: if at a given pressure R12 evaporates at 45F and the evaporator outlet temp is 50F the gas would be 5F "super-heat".

I have a program at work with the math formula and pressure/temperature charts. I've never seen one used in an auto shop.

Glad to know the problem for you was just the variable orifice tube...42F @ the vent is excellent...I could remember trying the VOT with R12 years ago and found the temps would not drop below a certain point...

I need to remember the experience you had for the next time someone tries that and it doesn't work... But then again, most folks will not have R-12 to play with anyway...I still have a full canister for certain situations...But except for the 84 Ranger everything I own has R134a in it...

 

[weston vance]

replacing orifice tube

Glacier,
My Haynes shows 32oz, R-12 and I even called my local Ford dealer to see what they call for, 32oz R12 1993 and earlier. Just for ***** and grins I did recover 4oz, no difference in vent temp. New fan clutch today, no difference in vent temp.

I think I fuked up putting that variable orifice tube in my R-12 system. That tube is designed to restrict flow in a 134a retro. That restricted flow keeps the the refrigerant in the condenser longer and produces more sub-cooled refrigerant.

My theory is the variable tube is producing too much sub-cooled refrigerant in the R-12 system and flooding the evaporator. My pressures are perfect @1500rpm Low 35psi High 280psi ambient 104F center vent temp 54F. Not a lick of difference at 60-65mph still a lousy 55-60F center vent temp.

That vent temp should be 40-45F. I pinned my outdoor blend door shut I have not tried pinching off my heater hoses yet, but I really think the variable tube is the problem.

this is my fathers truck, so im nit that familiar with it didnt realize it uses r 12 rather than r 134. im trying to figure iut how the get the low side line loos to get to the orifice tube. a/c cools preetty good until you hit the road. i'm assuming the orifice tube is clogged. what do you think??

 

[Joes4x4Ranger]

this is my fathers truck, so im nit that familiar with it didnt realize it uses r 12 rather than r 134. im trying to figure iut how the get the low side line loos to get to the orifice tube. a/c cools preetty good until you hit the road. i'm assuming the orifice tube is clogged. what do you think??

The orifice tube is actually in the high side liquid line. Look under the accumulator and low side lines. That small black line that is coming from the front of the truck is where the orifice tube is. Take your intake tube and air filter box out, the liquid line should be easy to get to with that out of the way.

Sounds to me like you are low on refrigerant. At idle you have just enough pressure to keep the clutch from cycling. Se if the clutch starts cycling real fast when you hold the rpm at 1500.