A/C and heater problems

Tiny
CADDY74
  • MEMBER
  • 1974 CADILLAC EL DORADO
  • 8.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 56,300 MILES
A/C doesn't blow cold air. Heater blows hot air constantly when car is on or when engine is running will not stop even when A/C is on. A/C shop Evacuated r12 from A/C system changed fittings and recharged with r134. Cold air for a few days then it stopped.
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Sunday, June 16th, 2019 AT 4:55 PM

5 Replies

Tiny
STEVE W.
  • EXPERT
Welcome to 2CarPros. The description sounds like the A/C has a leak. R134A has a smaller molecule size than R-12 and will even leak through the hoses. I would start by checking with a set of gauges to see if there is any charge in the system. Then recover and vacuum the system down and see if it holds. If not then you will need to repair whatever is leaking.
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Monday, June 17th, 2019 AT 1:33 AM
Tiny
CADDY74
  • MEMBER
Thank you. I will check everything on Monday 6/17/19.
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Monday, June 17th, 2019 AT 2:59 AM
Tiny
STEVE W.
  • EXPERT
A common issue with retrofits like this unfortunately. There is still R-12 out there but finding a shop to do a full flush and recharge can be expensive. Another thing to check would be the heater control valves to be sure the heater core air is being stopped. I have added bypass valves on some of the older vehicles to help the A/C work better by diverting the hot water so it doesn't go through the heater core when you turn the temperature to cold and A/C.
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Monday, June 17th, 2019 AT 3:42 AM
Tiny
CADDY74
  • MEMBER
I will check the heater control valve today 6/17/19. Thank you for your advice.
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Monday, June 17th, 2019 AT 2:02 PM
Tiny
STEVE W.
  • EXPERT
You're welcome please let us know what you find.
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Monday, June 17th, 2019 AT 2:16 PM

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