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Item Posts    Sort Order

A/C expansion valve hiss

 
scutdude
User
Posts: 62
Joined: 09/07
Posted: 07/06/13 10:47 AM

I live in Texas. Running 98 degrees outside. My expansion valve makes a periodic hissing sound. Is my valve bad, or am I low on freon, or is it working as is should?  I'm running R134.

Anyone know what my high an lo side pressures should read?  

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waynep712222
User
Posts: 223
Joined: 04/13
Posted: 07/06/13 11:31 AM

just curious...

do you have a SIGHT GLASS installed in your system so you can verify the charge by the lack of bubbles going past??? most fords had them ..

i always aimed for 220 to 235 on the high side.. but i am not a qualified AC tech.. i only dabble on my own stuff.  

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scutdude
User
Posts: 62
Joined: 09/07
Posted: 07/06/13 06:53 PM

I have a sight glass, but was told not to count on it with R134. Are you running R134 and having good luck with the sight glas?  

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70bird
User
Posts: 86
Joined: 07/13
Posted: 07/07/13 09:38 AM

Hello scutdude


You can not use a sight glass with 134 on an r12 mustang, it will often look empty when it is full, lol,.

When exactly does it hiss? They often do this for a few seconds when when it is turned off.  

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70bird
User
Posts: 86
Joined: 07/13
Posted: 07/07/13 09:38 AM

Hello scutdude


You can not use a sight glass with 134 on an r12 mustang, it will often look empty when it is full, lol,.

When exactly does it hiss? They often do this for a few seconds when when it is turned off.  

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scutdude
User
Posts: 62
Joined: 09/07
Posted: 07/07/13 05:50 PM

It makes a periodic hiss when the compressor is on. Roughly every 15 seconds. Air is cold, but not as cold as I would like it to be. Also, utilizing a rotary compressor.  

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70bird
User
Posts: 86
Joined: 07/13
Posted: 07/07/13 06:29 PM

Hello


Is this positively a new sound, id so when did it start?

R134 does not cool as well as r12.

Rotary's are good.

If it's been hissing for long it would be empty by now if it had a leak

Is the valve new?

Does it only hiss when the compressor is on?

Did you charge it your self?

If so do you have a machine or somehow pull a vacuum on it first before charging?  

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scutdude
User
Posts: 62
Joined: 09/07
Posted: 07/09/13 07:05 PM

All is new.  Took car to pronouns for evacuation and charge. Trying it figure out if I should take it back or if hissing expansion valve is normal  

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70bird
User
Posts: 86
Joined: 07/13
Posted: 07/09/13 08:11 PM

Hello scutdude

Well I still need to know exactly when it's hissing. But it's possible that your temp sensor is set too low which contributes to the ac not getting very cold. Unfortunately it will never feel really cold until it gets to around 75 degrees outside when you don't really need it, lol. Those systems aren't great at cooling and as I mentioned the 134 doesn't cool as well either.

Does your compressor switch on and off every minute or less?

Get a thermometer, and stick it in center vent, turn ac on high then drive at 50 mph with the windows up for 10 minutes. Tell me how hot it was outside and what the vent temp got to. If it's around 85 degrees outside the ac in the vent should be around 45-50. If it gets lower than that you are lucky.  

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