Looking for help, getting hot outside and I'm trying to figure this out at home.

AC compressor runs. Suction pressure 40 psi, discharge about 220 psi. Dryer and all hard lines are hot. If memory is right this should be cold. I'm thinking something clogged in evaporator or orifice tube but looking for advice before starting to buy parts. I would prefer to fix at home and do have access to a vacuum pump.

Had this car for about 5 years and typically add a can of Freon at the beginning of summer.

Any suggestions appreciated.

 

You could try adding dye and if there is a leak somewhere the UV light would show it. If it's a restriction the only places I could think of are the orifice tube or condenser as they have the smallest passages of the system.

When you added refrigerant did it contain additives like seal leak stopper? I read these are not good for the A/C and it could be a potential problem.

 

when you say "add a can" beginning of every year, do you mean the whole can?



assuming you have an f-body (you didn't say) then you have an orifice tube type of system and the pic above applies. output line from the compressor to the condenser should be hot, the output from the condenser should be cooler but still warm.
** from the condenser to the orifice tube location should be warm and there should be no noticeable chance in temperature using your hand, if there is then that's where the blockage is.
the only blockage should be where the orifice tube is, which by definition is a restriction and causes the pressure change of the refrigerant from high (150+ psi) down to 30-50 which then causes cold. After the orifice tube the piping and lines should be cold.
the evaporator is behind the firewall inside the dash so you won't be inspecting that,
the output line from evap coming through the firewall then goes to the aluminum accumulator can which should be cold (and wet if there is humidity in the air outside) and then that hose from accumulator back to suction side of compressor should be cold/cool, and at no point from evap output back to compressor should there be an abrupt temperature change (like on the high side)... if there is then there's a restriction.

if that checks out, chances are you have air in the system displacing refrigerant and greatly lowering cooling performance of the system, you would need to evacuate it with your vacuum pump then recharge.

 

[QUOTE=1 FMF;19296970]when you say "add a can" beginning of every year, do you mean the whole can?



assuming you have an f-body (you didn't say) then you have an orifice tube type of system and the pic above applies. output line from the compressor to the condenser should be hot, the output from the condenser should be cooler but still warm.
** from the condenser to the orifice tube location should be warm and there should be no noticeable chance in temperature using your hand, if there is then that's where the blockage is.
the only blockage should be where the orifice tube is, which by definition is a restriction and causes the pressure change of the refrigerant from high (150+ psi) down to 30-50 which then causes cold. After the orifice tube the piping and lines should be cold.
the evaporator is behind the firewall inside the dash so you won't be inspecting that,
the output line from evap coming through the firewall then goes to the aluminum accumulator can which should be cold (and wet if there is humidity in the air outside) and then that hose from accumulator back to suction side of compressor should be cold/cool, and at no point from evap output back to compressor should there be an abrupt temperature change (like on the high side)... if there is then there's a restriction.

if that checks out, chances are you have air in the system displacing refrigerant and greatly lowering cooling performance of the system, you would need to evacuate it with your vacuum pump then recharge.[/QUOTES

Car is 99 Z28 so diagram should be right. Every year it took a full can but always had a little pressure, hard to see air leaking in. No dye or stop leak used.

I'm guessing a plugged orifice - will check this weekend. Any hints on where this is located? The

 

Sounds low on freon or a blockage in the system.

 

The orifice tube is in the hard line coming from the top of the condensor on the expansion valve side back toward the firewall. Unbolt the hard line on both sides (makes it easier to get to without bending the line too much) and you can reach it with needle nose pliers.

It's only a $5 part but you have to open up the system to get to it, meaning you have to vacuum the system, add refrigerant (I believe yours holds 24oz of 134a but I'd check that first), and you should probably replace the accumulator since the system has been opened.

Hope that helps.

 

You can buy the receiver/drier and exp tube for as little as $30...and for as much as $50-$60. I'd suspect a slow leak if you're adding a can every year. Add some dye if you recharge it again.