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Old 08-25-2015, 12:00 AM   #1
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Default 91 Roadmaster AC problem

My AC works well for about a half hour then dies off , and then one of the pipes ice up . It takes the old type refrigerant which I have but my son thinks it some thing else . Any ideas ?

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Old 08-25-2015, 12:05 AM   #2
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What dies off? Air flow, or does it go warm?
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Old 08-25-2015, 12:07 AM   #3
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What dies off? Air flow, or does it go warm?
Blow warm air . TheReaper!
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Old 08-25-2015, 12:20 AM   #4
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You'll need to check both pipes coming out of the cabin when it is doing this. If both are cold when you grab them when the issue is occurring, you may have a blend door issue, usually caused by a bad actuator. If one of the pipes is cold, and the other isn't, you'll need to check (or have checked) the system pressures to see what is going on. It is possible for the system to freeze up even when it is low on refrigerant. If the system is actually freezing, there may be other issues as well, but you will be able to get a better idea by looking at system pressures.

Many systems give up after a while as well if they see the low side pressure switch being tripped too much, and many will even set a code when it kills the A/C, however the code does not turn on the Service Engine Soon light.
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Old 02-21-2016, 02:29 PM   #5
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Default juice ?

OK we finally got around to this and found out that the AC is getting juice when the heater is turned on . In the winter when we had the heater on it was not working very well , but with the wire to the AC disconnected it works fine plenty of heat according to my son . Also he installed a new thermostat with no change . Any ideas ?

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You'll need to check both pipes coming out of the cabin when it is doing this. If both are cold when you grab them when the issue is occurring, you may have a blend door issue, usually caused by a bad actuator. If one of the pipes is cold, and the other isn't, you'll need to check (or have checked) the system pressures to see what is going on. It is possible for the system to freeze up even when it is low on refrigerant. If the system is actually freezing, there may be other issues as well, but you will be able to get a better idea by looking at system pressures.

Many systems give up after a while as well if they see the low side pressure switch being tripped too much, and many will even set a code when it kills the A/C, however the code does not turn on the Service Engine Soon light.
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Old 04-16-2016, 01:12 AM   #6
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Agree maybe the low-pressure switch is faulty? This is the one that connects to the accumulator.

When it [freezes up?] again:

1. Disconnect the plug to the low-pressure sensor
2. Keep blower on high
3. Wait for that pipe to de-ice itself, it doesn't need to get hot but needs to mostly warm up
4. Wait an extra minute
5. Reconnect the low-pressure sensor
6. Now you should hear the compressor engage and get cold air back for a while until it [freezes up?] again

If my test works I speculate it is probably this sensor incorrectly signalling "low-pressure keep pumping woohoo" to the compressor. $14ish at Napa. If not then you're out $14ish and have replaced something that likely needs replacing anyways.

Let us know how it goes!
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Old 04-16-2016, 10:35 AM   #7
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OK we finally got around to this and found out that the AC is getting juice when the heater is turned on . In the winter when we had the heater on it was not working very well , but with the wire to the AC disconnected it works fine plenty of heat according to my son . Also he installed a new thermostat with no change . Any ideas ?


Juice? What the heck does that mean?
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Old 04-16-2016, 10:53 AM   #8
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The compressor is getting powered. At least that'* what I am gathering from it
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Old 04-16-2016, 10:07 PM   #9
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Is the compressor running when the air goes warm?

If pressures are ok, then I agree the first thing I would look at is the pressure cycling switch.....
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Old 08-06-2016, 09:39 PM   #10
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Correction this is a 1993 Roadmaster , our Park Avenue is a 1991 .

UPDATE

Well I was finally able to pry this away from my kid , the fact that that A.C. wasn’t working and it’* like 90 every day , might have had some thing to do with him letting loose ? Any way I got it into a shop that actually knows what they are doing . Keep in mind I am not a mechanic nor do I know any of the lingo . It seams that the previous owner or the care taker had some one work on it . According to the shop it’* at now , they had it over filled and the inlet and outlet was some how epoxied closed . They replaced the accumulator and the manifold hose assembly . recharged the system . Now it is working but there is still some thing wrong with it . According to the mechanic the A.C. runs all the time as in summer and winter , and when some thing goes wrong the control goes into default and tries to go to –40 degrees F and then freezes up . It’* working perfectly except the other night I was on the freeway with it going full blast , I rolled the window down a bit to have a smoke . By the time I finished my smoke the unit froze up . I shut it off drove anther 7 miles in about 7 to 8 minutes , I turned the air back on and it’* been running perfectly ever since . That said I have tried the smoke thing again . I asked the mechanic if he thought getting another control would help , he said that he doubted it would make any difference . According to him it’* design that just doesn’t work very well , any one here ever own a Roadmaster with these kinds of problems ? Right now the plan is to drive it as is and come winter disconnect the juice to the compressor . Any suggestions , comments etc. etc. . TheReaper!
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