Since warm weather is just around the corner I need to get my A/C fixed. I filled it with new coolant and it lasted good for a month, but it eventually leaked out. I used the leak test stuff that you put into the AC lines and you use the glasses and the light to check for leaks however did not find the leak. Where are the most common places to check for leaks or even replace? I thought about buying a new seal kit but wanted to get some opinions first. Thanks all. 

Found mineral oil here to be the least expensive.

 

https://www.oreillyauto.com/detail/b/murray-climate-control-4379/chemicals---fluids-16461/air-conditioning-chemicals-16497/refrigerant-oil-12459/cafa2aa02793/murray-climate-control-mineral-oil/59000/4521683/1992/volvo/940?pos=0.

22 minutes ago, IBMobile said:

Found mineral oil here to be the least expensive.

 

https://www.oreillyauto.com/detail/b/murray-climate-control-4379/chemicals---fluids-16461/air-conditioning-chemicals-16497/refrigerant-oil-12459/cafa2aa02793/murray-climate-control-mineral-oil/59000/4521683/1992/volvo/940?pos=0.

Thank you, I will be picking that up.

On ‎3‎/‎12‎/‎2020 at 8:13 AM, IBMobile said:

O-rings should be coated with AC mineral oil and not PAG oil before installation.

 

Just curious as to why not coat with PAG oil.

 

- John

From "BASIC AIR CONDITION REPAIR" article in 2ed generation 24 valve cab interior. 

Always replace the o-rings when working on an open system.  They are a possible point of future leakage, and it’s cheap and easy to do.  All O-rings need to be coated with A/C mineral oil NOT PAG oil.  PAG oil is hydroscopic and will cause corrosion on the outside of the hose fittings and O-rings.

Always learning something new.  Thanks @IBMobile.

 

- John

Sorry for chiming in late on this, so far some real good suggestions. 

While at it replace the schrader valves, service ports. When I got my old truck the AC was dead, had less than 15 psi static pressure in the system. Being the cheap axx I am I just dropped in 16oz R34a and a ½ oz oil.  Worked good, probably should have evaced the system but hey it was hot out and I did not want to waste the time. Anywho ta month later the system was empty again I checked it with a UV lamp. No leaks  except the schrader valve on the fitting. I shrugged it off as maybe a bit that came out when I disconnected the gauges. Charged it again and this time cleaned off the schrader valves (high and low) with acetone (brake cleaner). Yep a month later same thing and the stame green glow returned at the schrader valves.  OK fool me once, YA I get it. So r&r the fittings/schrader valves, added some oil (PAG and pulled a 250 micron vacuum AND IT HELD! filled system (sorry can't remember the amount) been two years now and still cold 

 

As a side note getting rid of the puke bottle and running the road draft tube under the truck and behind the cab as well as replacing the oil covered radiator allowed the fan to pull the heat from the condenser a heck of a lot better than it was. Doing this lowered the high side pressure quit a lot and dash vents are cold at idle on the hottest days

Edited April 2, 20205 yr by NorCalAndrew

I haven't forgotten about this thread but have been lazy, I wont lie. I have a 68 Chevy C10 that I have been focusing on. However, this weekend, I tackled the AC system. Went nice and slow, all came apart as it should. The plastic on the dash is quite easy to crack I quickly learned. I got my HVAC box taken apart, but as luck would have it, I received the wrong A/C Evaporator Core. I have to use my truck this week, so I buttoned it all back up and am currently waiting on my new Evaporator. I didnt take many pictures but will do so since I get to do this twice!! I think the next time will go more quickly since I know what I am doing. 

On 3/12/2020 at 10:13 AM, IBMobile said:

While you have it apart the accumulator should be replaced along with the orifice tube and all the 0-rings.  The O-rings should be coated with AC mineral oil and not PAG oil before installation.   You will need to add 2 ounces of PAG 100 oil to the system for the replaced evaporator and 2 more if you replace the accumulator. 

 

You may want to replace the fan motor; it's old and tired and dido for the heater/AC blend door coupler.  

 

https://heatertreater.net/dodge-ram-95-02 

 

 

IB Mobile, for the heater treater part to fit, does the vent setting need to be on a specific setting for the heater treater part to fit on? I tried putting mine on, however it would never line up, essentially like the motor was not on the right setting, the gears inside and i didnt want to try and force it. I am sure it is listed somewhere, but cant find that info.

I had the HVAC box off for install but I had to index the the motor. The part came with a 9v battey and instructions on how to do that. Then l aligned the door with the motor position. I however do not remember the process. I take it yours did not come with anything like that?

The last one I did was @JAG1 's work truck where we pulled the dash and HVAC box out. 

Before disconnected the wiring and vent hoses:

•  turn the ignition switch to the on position
•  set the heater knob to the 12 o'clock position, straight up and down
•  then turn the ignition off once the door has rotated; about 30 seconds.

  This will "index" the blend door and motor to the middle position and make it easier to work with out getting the door hung up on a side when putting it back together. 

Jag1 is really glad IBMobile did it for him too  It like a new truck as neither the heater nor the AC was working. IBMobile is walking magic 

Edited July 7, 20204 yr by JAG1

I would like to know what to do if your blend door is stuck on cold as mine is? Dont know if it is the the motor or maybe the blend door is stuck.

 

I know what a McQuiver but not what a McCobb is. A cobbiler togetherer of things?

1 hour ago, IBMobile said:

This will "index" the blend door and motor to the middle position and make it easier to work with out getting the door hung up on a side when putting it back together.

 

Yup been there done that and ended up breaking the blend door shaft. His suggestion is best yet. I had the blend door on full cold and when I put it back together caught the blend door on the wrong side of the case stop. Hence when I spun it to full hot the motor took off and forced till it broke the blend door shaft. 

29 minutes ago, dripley said:

Dont know if it is the the motor or maybe the blend door is stuck.

 

Check the blend door motor: 

• battery voltage (>12V) at pin #1 DB (dark blue) wire.  
• 0 to <12 volts at pin #2 YL/OR (yellow with orange tracer) wire when turning the heater control knob.
• <10 ohms at pin #3 between BK/LG (black with light green tracer) and ground. 

If all above are good then either the motor is bad or the door is stuck. 

 

 

I did get my entire HVAC box out, twice..as I had to use my truck in between taking it apart and waiting on my new evaporator core to arrive. It arrived yesterday and I put it all back together. I went to my dads and we charged it, the AC is blowing nice and cold. It vacuumed down quickly and no issues putting the R134a back in. Gonna run it a few days, make sure it continues to cool nicely, the air coming out of the vents is ice cold! I did put my HVAC box all back together, however it does have the plastic blend door coupler on it, as I did not change the control knob to the 12 o'clock position. I did however install the stud and nut on the rear of the actuator motor so i am hopeful I can get the heater treater part in by pulling the carpet back just a bit to get to the rear stud/nut. I do have pictures that I took and will upload those just for reference in case anybody needs them in the future. What a mess though, pulling the dash twice was not fun. I thank everybody for their help with this!