In many Blossom Valley homes in San Jose, the heating and cooling equipment that came with the house is now around 40 years old. A lot of it still runs. The real question in the 95123 and 95136 zip codes is usually not whether the old system works, but what it costs to run through a warm South San Jose summer, and whether the next failure is worth repairing.
What 40 years does to a system
Equipment of this age was built to much lower efficiency standards than new systems must meet today, and it has lost ground since it was new:
- Compressor wear. An aging compressor starts harder and moves less heat. A failing one may hum without starting or trip the breaker.
- Coils. Decades of dust on the outdoor and indoor coils cut how much heat the system can move, so it runs longer for the same result.
- Refrigerant. A system this old most likely uses R-22. With R-22 no longer made in the US, any leak repair has to be weighed against the price of the recovered refrigerant needed to refill it.
- Ducts. Joints loosen and insulation thins, so part of the cooled air ends up in the attic.
- Furnace heat exchanger. In an old gas furnace the heat exchanger can crack. A crack can let combustion gases into the air you breathe, which makes it a safety problem, not a comfort one. Keep a working carbon monoxide alarm near the bedrooms in any home with gas appliances, and if it sounds, get everyone outside.
Why the cooling bill is high
High summer bills on an older system usually have more than one cause. Before anyone talks about a new unit, these are worth checking:
| Check | What it tells us | Usual fix |
|---|---|---|
| Filter and indoor coil | Whether air moves freely across the coil | New filter, coil cleaning |
| Outdoor coil | Whether the heat leaves the house easily | Coil cleaning, cutting back plants |
| Temperature drop across the indoor coil | Whether the system cools as it should | Points to an airflow or refrigerant problem |
| Duct runs in the attic | How much cooled air reaches the rooms | Sealing joints, replacing failed runs |
| Thermostat schedule | Whether the system runs when nobody is home | New schedule or a smart thermostat |
Some of this is a maintenance visit; some needs a repair. If the bill stays high after the easy fixes, the equipment itself is what costs you money.
Repair or replace a 40-year-old system
Age alone is not a reason to replace a system that still heats and cools well. These are:
- the compressor or the outdoor coil fails;
- an R-22 system has a refrigerant leak;
- the furnace heat exchanger is cracked;
- the system has needed a repair every season for the last few years;
- the house stays uncomfortable even when everything works.
A single failed capacitor, contactor, igniter or fan motor is usually worth fixing, even on an old unit, and most repairs fall between $89 and $500. The diagnostic fee is waived if you go ahead with the work. Our repair-or-replace guide shows a worked method for the cases in between, and AC repair and furnace repair explain what a repair visit checks.
Choosing the replacement
Plan it before the system fails on the hottest afternoon of the year:
- Furnace and AC, or a heat pump. San Jose winters are mild, so a heat pump can heat and cool with one system. A new gas furnace paired with a new air conditioner remains a straightforward choice.
- Size it again. A house changes over 40 years: new windows, added insulation, a converted garage. We calculate the load for the house as it is now, not as it was built.
- Check the electrical panel. A heat pump or a larger AC may need a new circuit, so we check the panel during the estimate.
- Fix the ducts with the equipment. New equipment on leaky ducts still loses its air into the attic.
A new system typically runs $4,500 to $15,000, depending on the equipment and the duct work, and the estimate is free. You approve the price before we start.
Local notes
Summers in this part of South San Jose are warm, with afternoons often in the 80s and 90s °F, and old systems feel it most in a heat spell. A spring tune-up is the cheapest way to find a weak capacitor or a dirty coil before then. Same-day service is available for most calls received before noon, and urgent calls are taken 24/7. We work on all the common makes, including Carrier, York and Daikin. San Jose HVAC Pros is an independent company, licensed, bonded and insured, serving San Jose since 2009.