A/C blows hot

[spastic_chicken]

Anyone good with A/C? I have a 134a converted system (Done before I got it) That blows hot. The switch is bad, the clutch wouldn't engage. So I jumpered the clutch to 12 volts to see if it would engage. Luckily it did. So I tried to fill it, and it'd cycle from full to empty, still blowing hot. What do I check for next?

[msc0nduct]

I don't know but I sure wish I had a/c or even a heater that stops blowing hot air.

[Guest]

what exactly is it? you said the clutch is engaging, the system is charged. did you replace the orifice tube when you converted? According to some, that can get blocked with debris and prevent coolant flow.

have you checked for problems in the air mix door - it's possible you have vacuum or electrical problems that select cold air/warm air based on the temperature setting you have selected.

There is some electrical testing you can do on the control head as well, but that's a bit detailed to go into here

[spastic_chicken]

It was converted before I got it, not sure if the orifice tube was changed. If I adjust the temp slider on the air-mix you can hear the door opening and closing, so I don't think it's that. I'll look into an orifice tube.

[Guest]

you should be able to remove the glove box and look at the air mix door stuff move. i'd try that before ripping out all the plumbing. but yeah, short of electrical problems, the orifice tube is probably the next place to look. let us know what you find!

[Beladona_13]

Anyone good with A/C? I have a 134a converted system (Done before I got it) That blows hot. The switch is bad, the clutch wouldn't engage. So I jumpered the clutch to 12 volts to see if it would engage. Luckily it did. So I tried to fill it, and it'd cycle from full to empty, still blowing hot. What do I check for next?

As I read this, your clutch won't engage until you jump it. This may be because of low pressure, not becuase the switch is faulty.
I would put some gauges on it and see what pressures you have. The condition you are describing sound like a leak caused you to lose all of your refrigerant. If this is the case, you cannot simply "fill it". you first need to evacuate the air from the system so that you have room for the R-134A. If there is a leak, your system will not hold a vacuum.
You won't be able to get much, if any, refrigerant into the system if it's full of air... and the kicker if it's lost all of it's pressure... it'll blow hot air!

Let me know if I can help further... I've been doing A/C & retrofits for 15 years.

[Morella]

Most people won't even answer your A/C questions unless you tell them what the pressures on your gauges were reading while you were troubleshooting...not because they are assholes, but because there isn't enough useful information to give you an intelligent answer. What you are going to get is something general like this, which may or may not help...

Since 1977, GM has been using a system that cuts out the compressor when the pressure on the low side is too low, in lieu of blowing a fuse when the compressor closed a superheat switch, which was the previous plan. There is never any reason to bypass this switch, unless you suspect the switch itself. If the system charge is too low for the compressor to run, and it has not been run completely out, one has merely to begin putting in the refrigerant. When the static pressure is high enough for the switch to close and compressor to run, it will start, the pressure will drop, and it will cut out, over and over again, until there is enough refrigerant in the system for it to maintain a continuous operating pressure that is within limits. The system can then be steadily brought up to the proper charge.

-denise

[spastic_chicken]

I put in 3 cans, the gauge does something funny, it goes from low to high, cycling. I'll have a set of gauges to put on it this weekend.

[spastic_chicken]

I bought a set of A/C guages, High side and low side are both empty. I think I should start hunting down a leak.

[spastic_chicken]

Found several leaks in the condensor.

[Morella]

Seeing that it is a 134 conversion, you may want to talk to one of the agencies like ackits.com or aircondition.com that specialize in parts for the conversion. A new parallel-flow condensor will give you much better performance with 134.

BTW, the orifice tube is nothing but a plastic piece of tubing with a screen in it. I usually replace them when I do an evaporator flush, but the only time I've seen one clogged enough to do harm was in a 78 Cadillac that sat empty for a few years. That causes the system to fill up with congealed oil (that orange crap).

Best of luck,

-d

[spastic_chicken]

I got a new condenser and replaced it. Pulled a vaccum on it, and it still leaked a little. I ran some of the UV leak stuf through it, I can't find any UV dye anywhere! The clutch still doesn't want to engage, but if I jumper it to 12 volts I can get it to engage. With the compressor is on, it doesnt seem to take a recharge at all, one can and it's like I didn't even fill it. Granted, this is a 14 ounce can, and the A/C system needs 2.7 pounds.

[Morella]

> Pulled a vaccum on it, and it still leaked a little.

Are you sure you got the right O-rings on the condensor fittings, and did you put some Ny-log on the threads? I would have had the hoses redone, replaced the acc/drier and all of the O-rings in the system, flushed and purged the evap and replaced the orifice tube. I'm not saying this to be bitchy, but because I have learned that if you don't do the job right the first time, it is just going to cost you more money later.

The clutch will NOT engage until there is enough refrigerant in the system to bring the static pressure above the low side operating limit. This usually takes at least one can of refrigerant, then it will kick in and out as you put the second one in, and usually it is running steady by the time you put the third one in. If you keep jumping the compressor and turning it on with no refrigerant in there, it will burn up.

What were your static pressures after the first can was put in? When you jumpered the compressor and started it, what did they go to then?

-d

[spastic_chicken]

Ballpark what do you think it runs to have the lines done? I'm eventually going to rip the engine and trans out of this vehicle and transplant it into the hearse. The condenser was clearly leaking, so I replaced it. I was just hoping that was all that was leaking.

I wrote down what the pressures were, but left it in the truck, I'll get back to you. Thx

[Morella]

I think it cost me somewhere around $75 to have the hoses redone on my 76 coach. The liquid line (the small, long one) usually doesn't go bad. It's the two thick hose assemblies that need to be done, with barrier hose. I also asked the shop that did them to sell me all of the new O-rings, so that I didn't have to go search for them.

-d